It comes off the back. I used them during a tubing trip down the river and they stayed on my feet as well as let the water out. He was on the phone to me in central London using the £100+ bluetooth Shure cable. par contre semble facile d’installation I went with the kids size because I can usually wear them but these ran big and I have a narrow foot. Last week the insole started to creep out, and yesterday it fell out entirely. Smaller than i expected but worked for what i wanted. I love them so much and they are just what I wanted. I will contact the seller directly. The only set back in my opinion is the speaker sound quality; is scratchy and you have to be in a quiet place to hear the person clearly.