I've been wanting these all of my life, I just didn't know it. They solve the problem of being able to listen to music while exercising without giving up your situational awareness. I've used a bluetooth speaker on my bike, it disturbs those around you and is not easy to transfer from road to mountain bike. In fact, it's not secure on a mountain bike. I've recently been using airpod pros, but even in transparency mode, you do not hear everything around you well. These solve all those issues. I use them for walking/hiking, mountain biking, road biking, and rowing (on the water, not in the gym). They sound great. You need to have realistic expectations, they're not going to sound like a pair of Bose Quiet Comfort headphones, but they sound as good as you could expect for the form factor. Everyone I have let try them has been impressed. You do not have to turn them up super loud to be able to hear them clearly, which is what makes them great. Because they're not loud, you still hear what's going on around you and can even carry on a conversation with people. The bass is good at low and medium volumes. At high volumes the bass drops off, but I don't listen to them that loud. If you riding on the road, a passing truck will drown them out, but what do you expect? Secondly the controls are excellent. The single button for pause, answering the phone, skipping a track, and going back a track works well. Speaking of calls, the call quality is good on my end and the other end. The other control, the volume control, works great as well. Swiping your finger along the frame is easy and precise. So why did I give them only 4 stars? The main reason is the fit. They are too small for me. I am an average size person, 5' 10" tall, size 10-1/2 feet, all other body parts are average size (just ask my girlfriend). However these are too small in two ways. One, they are too tight on the temples. this causes several problems. One is that they are slightly uncomfortable, but they really don't bother me anymore. Secondly, because they are pressing more on my temples rather than where the arms wrap around the back of my head, the slick plastic part of the arms are gripping my head instead of the rubber coated part of the arms. This means they can slip forward with a lot movement or bouncing. This can be a problem when mountain biking. The other problem with the small size is that the speaker is farther away from my ear. Look at the picture of where the speaker is relative my ear vs. where the speaker is on the model in the Bose ad. The second reason I deducted a star is the difficulty in swapping the lenses out. I love that you can switch the lenses, it's just not very easy. BTW, if you're old like me and have trouble seeing your bike computer without readers, I recommend using a Hydrotac stick on bifocal lens. They come in a pair, but I just use one on the left lens and it works perfectly for seeing the bike computer and still seeing distant objects as well. Overall I am very happy with these and can't wait for them to make it in a larger size.