this item also works for water shoes.
i just came across it, and thought quite a few people including muself can use it.
i have no proproiception in my left foot, so anything slippery like water and certain shoes, especially Croc sandles, i go flying. showers i have to be very careful in. This product is made for water.
i plan or ordering some and putting a couple pieces on different shoes, including a shower shoe. This is the stealth rubber used for climbing. It may also be useful for hand helpers/grippers.