Devices with internal flexibility sipes, such as slits, provide improved flexibility, improved cushioning to absorb shock and/or shear forces, and improved stability of support. Siped devices can be used in any existing product that provides or utilizes cushioning and stability. These products include human and other footwear, both soles and uppers, as well as orthotics; athletic, occupational and medical equipment and apparel; padding or cushioning, such as for equipment or tool handles, as well as furniture; balls; tires; and any other structural or support elements in a mechanical, architectural, or any other product.