Stop your water stone sliding all over the bench. This one is made in Taiwan of #304 stainless steel (not chrome-plated) and has three non-slip rubber feet for extra purchase on the bench. Designed so you can suspend your stone in a water bath when not in use. They will hold stones of any width and thickness and a length of 180 - 230mm.
Shown here holding the popular double-sided King Bench Waterstone that is not included.