I had bought several of these, but I don't think I'll be using them, so I'm putting them up for sale. This is a new, unopened item. #artisan #アーチザン #mouse_feet Excerpt from the official website: The design incorporates a unique "multi-curve shape." In addition to the rounded edges that prevent snagging, the sliding surface also features a two-stage curved shape with a slight curve, designed to reduce unintended excessive sinking resistance caused by uneven weight distribution.