NANK Runner Diver2 IP68 Waterproof Bone Conduction Headphones with Built-in 32GB MP3 Player, Bluetooth 5.3 Open-Ear Wireless Headset with CVC6.0 Mic - Perfect for Swimming, Running, Cycling & Gym Workouts

I recently acquired the 2nd generation runner diver 2. I have had it for about 3 weeks now and wanted to post a review.Of note, I had some issues with the first generation. After about six months, it stopped working, I received a replacement, and that stopped after about six months. Both were after a swim. The company replaced the first one and then replaced with the 2nd generation now which I am reviewing.I use these heavily for athletics. I bought it when training for a 70.3 distance triathlon. Music helps a lot with mostly solo training, so I was using it a few hours per week.Comfort: I found these to be comfortable in most uses. I use it swimming, cycling, and running. When swimming, I barely notice it. When I swim outdoors with a swim cap, the cap does put some downward pressure on the back, but I am able to adjust it to keep pressure off the ears. Running is no problem. It is lightweight and secure. Cycling is a little more challenging with sunglasses and helmet straps to work all these around, but I have ridden 3-4 hour rides and only mild discomfort.Sounds quality: I don't put a lot of weight on sound quality as I am mostly using this as background. I would say it is actually the best quality when swimming. Being in water seems to enhance the conduction. Cycling is a little more limited because of more background noise and wind. It is very good when running. I don't think bone conduction technology will ever give as good of quality as over the ear noise canceling headphones which I use for sedentary activities, but I am happy with the quality.Usability: I mostly use MP3 format and record. Bluetooth is not conducive with swimming. I prefer to not have a phone with me when running, and so bluetooth is also not useful then. It is simple to transfer and save files. It is harder during the activity to skip a song and so I am mostly limited to how I have saved the files. I do use bluetooth when cycling and it connects easily to my iphone. The control buttons take some learning as you only have 3 buttons and the rate or duration of holding the buttons help control features. This makes sense as you wouldn't want too many buttons. The location is an improvement over the 1st generation. It does require a proprietary charging device, but other than making sure I don't lose it, that is understandable as most USB or other styles would have issues with waterproofing.Microphone: I don't use it for phone calls. I used it x 1 for Discord while on a bike trainer. People could hear me, so it seems to have worked.Longevity: This is going to be my biggest question after my experience with the first generation. I believe the issue was waterproofing and the microphone. That is the main difference I see in the new construction. I swim with it a few times per week for a total of about 1.5 hours and will update this section if there are any issues or after about six months.Edit: It is now about 6 months later. They continue to work as well as day 1. The biggest concern I had was waterproof. I reviewed my stats and I have swam 28 hours which included pools, ocean, and fresh water lakes since I purchased these. I have not had any issues with water. The sound is very good in the water. That is where it excels. It does well running. When I am on my indoor cycling trainer with fan blowing, it does get a little difficult. The earplugs work, but unless people in my household are sleeping, external speakers are a better choice.In reviewing some of the other comments made since my original, fortunately I haven't had those issues. My first portable music was a cassette player-Walkman, so maybe I don't expect as many features. When I am using these, my main focus is exercise. The music is a bonus. I'm not going to take time to select different songs are playlist. I just set it before I start and let it go until I finish.I'm completely MP3 when swimming bluetooth to my iphone when riding, and a mix when running. The bluetooth connection hasn't ever been an issue. If I have left my phone in my car and forget I'm on bluetooth mode, I actually am about 100ft away before I lose the connection (or buffering if that is how it works).Overall, I am quite happy with this. It is a game changer for me for lap swimming especially. That can be very monotonous as I mostly do all my workouts solo. I also like this technology for cycling as it allows me to still hear and be aware of vehicles around me.