FINIS Duo Underwater MP3 Player - Bone Conduction Swim Headphones - Waterproof Audio - 4GB - MP3/WMA Compatible - 7 Hr

[Edit Oct 2022 after owning 18 months: After charging the unit yesterday, I discovered that the little green square cover on the charging plate had been lost, leaving a glob of glue, exposing the metal plate. Quick response from customer service: it will now leak and be ruined, and the one year warranty is gone. I was offered a discount on a new one. Disappointing, but I suppose 1 1/2 years in the water is an acceptable life for this fun device. I do not know if it is the amount of use or merely the age, but a glued-on part, whether merely left in storage or rubbing against my head and in water cannot be expected to last indefinitely. For now, I plan to either move the loose cosmetic tab from the other side over the charging plate (but what kind of glue to use?), or put a little piece of duct tape over it. That could give it an extended life, I suppose. Also, re my note below where I discussed the advice about cleaning the contacts, I never encountered any build-up on the contacts, so I did not need the calcium remover chemical; furthermore, given the apparent fragility of the glued-on part, I suspect exposing that to any unnecessary chemical attack may not be wise.]I have had my waterproof Finis Duo MP3 player for 5 months, swimming laps in pool 4x/week, and I like it. I have very little previous experience with other listening devices, but I wanted something for this purpose that would allow me to keep water out of my ears. The sound is fine for rock music, and my ability to decipher the words is no worse than a car radio, but it is way more enjoyable than counting strokes to myself.The sound bypasses the ear canal, eardrum and ossicles through bone conduction directly to the cochlea. I wear multi-use disposable silicone earplugs (CVS). Without them, the sound will not be as clear.Bluetooth apparently does not work through water, so you load the MP3 music files onto the unit’s memory directly from your computer, and can delete and/or add anytime (4GB of flash memory). I haven’t used iTunes for this, but one may need to convert iTunes music to MP3. The files I loaded onto my Duo were already MP3 files. I can only guess an MP3 book file would work, too, since I just read that those files are about 280MB for 10 hours; however, I don’t know what I would do if I missed an important sentence and had to go back.Finis company was very good at answering some questions I had via email. I got some tips from reading other reviews, too.You should charge the lithium-ion battery for 24 hours before first use—maybe it won’t hold a charge if you fail to do this the first time.You can charge on a fast charger on wall safely, but don’t store the Duo unit itself on the charger. Battery life claimed of up to 7 hours, though I cannot attest to that. I chart mine every 2 or 3 uses (half hour swims).It took me awhile to memorize the buttons and their use. I’m still unsure when the toggle at bottom is on random play or not, or whether that resets after turning the unit off. I also have another question for the company: Even though I turn it off before connecting to charging, why has it started playing recently when the charging finishes?I suggest looping just one of the 2 straps of your goggles to the unit if your goggles have an overlap in the front. I had to fiddle with this carefully for several weeks before deciding the best connection to avoid the device from lifting goggles off my eyes, while allowing the speakers to fit just in front of the ear over the zygoma, a.k.a. cheekbone. You may prefer to have yours on the insider strap loop, rather than the way I currently have mine (photo).Once I figured this out, I leave the unit attached to my goggles permanently to avoid breaking the clips.I noted a previous review suggested using CLR- calcium, lime and rust remover instead of alcohol, so I bought some, but have not needed it yet. Six hours at full strength as reviewer suggested may be excessive, because it took some of the finish off a faucet I tried it on. Bottle instructions say far less time and at half strength.

Don't think I'll ever be able to go back to swimming without one! First I have to say that I tried the Neptune, but that had serious problems and I exchanged it for the new Duo. This unit charged up in about 20 minutes. I was able to load up about 100 songs in about another 20 minutes.I am running a Mac Air with El Capitan. I used both iTunes and a flash drive to upload my music. I had a little bit of trouble safely ejecting the Finis Duo disk from the desk top. What finally worked was to move the Finis upload icon into the App folder and then drag it to the trash. This got me the 'safely ejected' message I needed.At the pool I had to fiddle faddle around a bit with the clips to get them onto my Swedish style goggles. It has to be said that I'm the MOST inept person on the planet when it comes to doing anything like this. But eventually I got them on. Anyone else wouldn't have a problem. Later I'll see how my bungee chord style goggles do with the clips and let everyone know how that goes.Music started right up, sounded AMAZING!! I wear ear plugs and a silicone cap over my ears and this didn't interfere at all with the sound. In fact, I think there may be a slight improvement in the sound quality of the Duo over the Neptune. I was able to turn the sound up a little while the speakers were on my head, even though I couldn't see what I was doing. There is play, pause, skip ahead and back capability, but I just listened to my playlist straight through. I don't feel that not having a display is going to be an issue for most serious swimmers. Really like that everything is in the cord behind the head and the clunky, look-like-a-tagged-dolphin display unit is gone. That's a real improvement. The 20 minute charge up time is a vast improvement over the Neptune also. The fact that my unit worked perfectly right out of the box is another very encouraging improvement. THANK YOU Finis for that!The speakers sit lightly on the goggle straps and didn't interfere with the fit of the straps at all. This might not be true for everyone, but I didn't have to readjust my goggles at all. I can't feel the speakers while I'm wearing the device either. I do a lot of side stroke and kick drills on my back, and the sound quality was still very consistent and good. I tried a few very hard flip turns and the speakers stayed put with the same sound performance. I didn't do any start dives because I never do, so I have no idea how they perform that way. While my head was out of the water, the sound was good, but it sounds better when my head is under the water. But it's not annoying when I swim my side stroke where my one ear is under the water and the other is out of the water. I tried a lap of breast stroke and I didn't find a noticeable difference.Now the reason I didn't give it the full five stars is that I want to make sure the device continues to allow me to upload new songs for my next work out. I also want to make sure it continues to work. I'll come back for an update and let everyone know how it does over the next few weeks.So, here it is a few weeks later. I'm ready to upload more songs and the Finis Duo upload file doesn't work. I'm using a Mac running Yosemite. The upload folder no longer appears on the desk top. Nor does it appear on my other computer running Windows. Not only that, but the usb doesn't even show up under systems of either computer which means there's no recognition capability at all. Unfortunately I'll be returning the device for a replacement. I tried contacting Finis but they are closed for the holiday. I'll be without any music at all for several weeks it seems, at best, and permanently if the replacement has the same problem. So once again, I'm deeply disappointed after a fairly large investment.