Calluses are a thickening of the skin due to increased pressure or friction. A callus usually occurs over a bony prominence such as the ball-of-the-foot, contracted toe, hammer toe or bunion. Some other factors that may cause a corn or callus to develop are poor fitting shoes or socks and activities that increase stress/pressure on the foot. Felt callus pads absorb pressure and friction to ease pain and help prevent callus build-up. Self-Adhesive backing. Can be trimmed to fit. 1/4" thickness. The center hole is precut and can be reveal by a slight push.