This is a classic pumice stone with a cotton strap. Proven for thousands of years, pumice stone is the natural way to remove calluses from hands and feet on a daily or weekly basis. The pumice stone should be used wet. Pumice is a natural product made of volcanic lava that hardly wears down and will last for many years. Perfect for rough skin on the elbows, knees, fingers, and especially - the feet! Stones vary in shape and size.