if you have any foot issues due to arthritis etc. Very slightly on the large side, but thanks to the elasticated fitting straps this is not too much of an issue. I am not sure on the material but I am able to wear them much longer than my other pairs without feeling like my glasses are being pushed into my head. Sound quality, connectivity, splash proof and easy to use. If you just run up on it, the ring slides to the head of the fluke and it pulls right out. Both work toghter. I open the trifold user manual to see how the wiring should be set through the maze of harness clips. "try a powered USB hub"didnt work. The sound signature is so hollow. I was able to get the medium and it gives me room enough to make it smaller.