What I like: Light, Comfortable, Good sound, Inexpensive, No volume control or other doodads that can fail.What I don't like: Cable joints are flimsy & vulnerable to damage (ALWAYS the reason I need to buy again...).My solution: Apply gobs of "liquid electrical tape" to reinforce weak areas.Now that Sony MDR-G45LP is gone, these ones are the best "el cheapo" headphones. The sound is decent, and they are pretty comfortable. Extra bonus for behind-the-neck headband option.I find the sound to be on the deep and muddy end. No crisp mids or treble to be found anywhere in these, making an equalizer really required. It certainly won't make anyone who is accustomed to listening to uncompressed/cds/flacs happy, but it does work fine for mp3's and youtube music which has poor sound quality anyway (what I use for when I exercise). The volume level is good enough to damage hearing but not really loud enough for me. If you've gotten no prior hearing damage you may find them loud enough but I find it irritating to have to have it at full volume. There is no volume control on the headphones, they are whatever your phone can output and that's it. My phone has an irritating habit of turning my volume down over the course of two songs so I have to keep cranking it back up - dumb hearing protection mode! It wouldn't be a problem if these were louder, but I need them to stay at full blast. As you can see from my photos, these are THE BEST headphones for people who wear glasses as the little skull pads do a GREAT job of stopping the ear pads from crushing your ears into your glasses into your head, which is super painful with most headphones because it presses the glasses frame into your skull and ear causing bruising. These totally eliminate that, just move them down a little on your ear like shown in my second photo, and no more pressure on the glasses frames at all! Great solution for people who can't wear earbuds and must wear glasses. I have a small head (21") , and small ears, and these fit me wonderfully. The headband is snug enough to actually stay on, something that's never been possible with other headphones (which apparently are designed for large male Neanderthals). I run and walk with these on and they don't budge. I imagine they would also stay on for weight lifting and other exercises too, but the cord might get in the way. They are truly a fantastic design for glasses wearers - now if they would just improve the sound quality they would have a perfect product! One final note: I thought that I would be able to hear traffic and stuff since these are not earbuds, but they actually block a lot of the surrounding noise. Bummer because I would like to hear when I am about to be run over by cars since I must run in the street due to lack of sidewalks in areas. I wouldn't call them noise cancelling in any way, but at high volumes like I like you really can't hear anything unless you pop one off one ear (which you can do since they stay on really well even if you pop one side off your ear a bit). Great headphones other than the pretty abysmal sound quality. Probably fine if all you listen to is rap but pretty terrible for guitar-based music: no high-end mids or treble at all. They don't grip enough to use in behind the ear mode on my size head - probably would be fine for Neanderthals. It's fine since I only run at night so I don't need a hat. If you run in the sun, keep that in mind!These are just like the Porta pros however I'd say that have a tad bit more muted treble. Not as crispy but they're still way up there for half the price and I won't be hurting if these break or get the five finger discount. Koss are the OGs, reject Bluetooth and embrace the cable.Sound quality:I directly compared this with the Sony MDR-ZX300AP Sound Monitoring Headphones (2x the price) and pair of Panasonic light weight headphones (1/2 the price). The Sony and this Koss had fantastic sound quality. Of the two the Koss was better, first it had greater clarity of sound and spoken word was more distinct and less muddy. Additionally this one was louder at he same volume setting. All else being equal a louder headphone indicates more money was put into the magnet and sound coupling efficiency-- hinting at the good engineering. The slightly cheaper panasonics were no match in sound quality, compactness, construction quality, though they get good marks for being the lightest (and thus highly comfortable for casual listening)ergonomicsUnlike the typical modern style of headphones this one has a plain (adjustable) spring metal bar over the head. This was actually slightly more comfortable than the Sony for the simple reason it gripped my ears more firmly so the top bar did not have to sit on my head-- something I find to be very uncomfortable. Now I've have more comfortable over the ear cans with padded head bars and also even more comfortable on ear ones as well but these were quite satisfactory while being much less bulky or heavy than heavily padded cansportabilityThe spring metal is not to make it cheap but is actually an engineering innovation. First, it's adjustable and heavy duty. This is to support the feature that when you fold this thing up you can compress then head bar. it becomes a tight coiled spring and there are two little hooks on the ear peice hinges that hold it tightly coiled. The ear peices then hinge into this folded state and the whole thing fits in a the tiniest space I've ever seen for headphones with only two hinge points. (your typical folding headphones either have more fiddly hinges to break or are novelty items with fragile plastic swivel joints that won't hold up to travel abuse in your backpack. others that use the same spring metal style are more flimsy and usualy cheap all over/)The only thing on these that looks flimsy is the foam ear coverings. They are thin, feel delicate and I expect I will tear them or they will oxidize and wear out. I see they actually sell new coverings so this is probably why.StylingNow the styling of these is definitely weird and combined with the metal head peice makes them look throwback if you set then next to a beefy Beats or Bose headphone. But I'd say the engineers defintiely triumphed here. It sounds good, it is rugged, it's compact and it's reasonably comfortable. The price is remarkably low for such quality.Conclusion:They put their money in these were it counted. They stole design styles from cheaper headphones but toughened them up and paired them with quality components. I really wasn't expecting these to be better than the Sony monitors but they were.these of course can't match the audio isolation of a quality branded over-the-ear noise canceling headphone but for $20 these are as good as you can get.Very nice. Good sound. Nice fit.Loved these while they worked. They didn't last much over a year though, as the headphone internals failed . Switched to JVC cheapies (about a tenner ) sound pretty good too, though the finish on the ear pads of those is now failing after almost 3 years of heavy use, but still sounding good. I might try Koss again at some point, and hope for better luck. I douse headphones a Lot every day (As I'm substantially deaf and don't want TV or Music blaring at high volume. TryingSkullKandy Bluetooth atm, nice, but I don't thinking bluetooth makes sense as I'm a heavy user, so possibly I'll look for something more solid soon from Koss. ?EDIT: i have bought 3 of these and all have had the jack break at 6-12 months (i.e. you only hear sound out of one ear unless you wiggle the wire).. three stars revived..Positives:These are awesome, incredible value for sound quality and build quality.- Compared to my sennheiser px100, i prefer these for the clean mids (amazing for vocal, classical and jazz) and cosy balanced bass (even for dub), although maybe the tops are sharper on the px100, and the fold away design better.- Compared to my Grado s80's the mid range holds up but the grado's are more comfortable both physically and acoustical (but are poorly made and fall apart easily).- Compared to my sennheiser HD25 (i.e. a closed not open design), the bass and treble is lacking, and they are far less efficient (i.e. less volume at same setting). But I don't like using the HD25 for pleasure as sustained music is fatiguing on the ear as they are too much like a reference monitor.- These headphones are 6 months old, used everyday at work & commuting, and are still working . The design means you can change how you want to wear them (normal or back) making them comfortable and flexible (with big hair or hats).NEGATIVES:- The bag they come with is a little small.- Open design not for everyone - leaks sound, sounds best at low volumes, does not isolate outside sounds.- Treble lacking- early 90's design not for everyone===================*Note these are open headphones and so produce a 'in the room' sound rather than a 'in your face'. For kids This design is good as they encourage low volume for full balanced sound, as well as leaking sound if played too load, warning parents.===================Two years later still using them everyday.. When the foam broke, I bought better pads for them, that improved sound, made them more comfortable and look less pants: https://www.amazon.co.uk/Replacement-Cushion-Porta-KSC35-Headphone-Black/dp/B00SWGQFIA/ref=sr_1_3?s=electronics&ie=UTF8&qid=1526453937&sr=1-3&keywords=koss+portapro+padsI bought these for the gym and was surprised how good they were. They look and feel cheap and flimsy, but they are tougher than they look, However there are issue with their comfort. The major selling point is their excellent quality of sound for the price. Ok if your are going to wear them in private and for short periods of time. A limited recommendation.ProsSound: The sound quality is fantastic for the price giving a balanced presentation that is sibilant free at the top end, clear and open in the mid-range giving good detail and impressive bass depth and weight. In fact having listened to many sources I would say that they are capable of giving a good account on reasonable quality DAB and CD or even uncompressed digital formats. The problem is that they are good enough to show the limitations of MP3, which means that even through an iPod touch playing higher data rate MP3 they can sound dynamically limited and lack drive to the music, so high energy music lovers may be disappointed.Price: good value for money.Small and pack awayCable: no microphone effect from the cable that is of good length with a integrated 3.5mm jack. Also comes with a converterConsLook cheap and flimsy: but are more robust than they look.Not very stylish.Comfort issues: would not say that they are uncomfortable all the time, but you may find yourself fiddling with them occasionally. I have worn them for two hours and found myself fiddling with them and I was most certainly aware that I was wearing headphones. Main problems are the head band that can gently press on the top of the head, especially for those with thinning hair and the pads above the speakers than can press on parts of the ear.Sound leakage: unfortunately open backed headphones have a much better chance of producing higher sound quality than equivalent priced closed cup models. Therefore the compromise for this sound quality is that they do leak sound and are not appropriate for public areas, noisy gyms are ok.I got these a couple of months ago having been through various sets of headphones/earphones to use with my MP3 player when on the train. Not being able to get on with the inner ear kind, I read existing reviews of the SportaPro's (and many others) before eventually paying out my money.From the first moment of listening to them, I knew my money was very well spent and the sound is simply fantastic for a pair of headphones at this price range. I mostly listen to metal - thrash and death varieties - where pounding bass and drums are essential - and these do not disappoint. In fact, I also have a pretty decent pair of big Sony's - MDR V700's costing nearly £80 - and it's now a toss up between those and the Koss'es when I listen to music at home. Of course, a pair of headphones is often only as good as the music players they're plugged into but these will improve the sound of most devices rather than using their usually poor bundled earphones. I've recently upgraded my old Creative Zen Micro to a high quality Creative Zen X-Fi and combined with the Koss headphones, my music now sounds the best I've ever heard it. Although they look fairly cheap, they're actually quite robust and don't mind being bent slightly out of shape when in my backpack: once freed, they simply pop back into shape again.If I do have any criticisms, there are just two minor ones: one, that they're pretty unusable in neckband mode due to the steel band "not feeling quite right" around the back of my head and secondly, that there should be small foam padding on the plastic slides that sit on top of your scalp during "over the head" mode.Overall, you're unlikely to get better for this price, nor for an extra twenty quid and they fully deserve the five stars I'm giving to them.I am hard of hearing and have found that these Koss "SPORTA PRO" Headphones are by far the best for use with my various microphone units. They are small & compact but still produce very good quality sound. Because of my hearing problem I have to listen at high sound levels. The sound quality is still excellent at these levels.The only problems that I have had is the flex breaking.I have 3 sets of these Koss headphones at this moment and I can highly recommend them.