It?s a Velcro strap! l cannot put it up the adhesive dont stick l want to return it would not recommend this orodyct to anyone want a refund and l could not get through to you since this virus l wanta refund l am a value customerthis will be my last time l eill ever order from you I think they are great! UPDATE: weve had them about 6 weeks and hes worn them nearly every day. Die Größe 39/40 von crocs war mir immer etwas zu kurz. They charge pretty quickly in their box which is nice because they only have about a four hour battery life, and I also love the fact that I can charge them up about three times before I have to recharge the box. Its very suitable for this kind of sandals. I think this is it when it comes to high end keyboard model. They should arrive Tuesday and Im eager to see if they work. I should have ordered two sizes up!