Not only are these functional, durable and comfortable bondage cuffs. The lining, on the inside of the cuffs, is made of a comfortable felt material. This allows the cuffs to feel good on the skin and not irritate (meaning you can squarely focus on the bondage play at hand and not the chaffing on the skin). They have an O-ring for connection to each other or other bondage devices. Specifications: The cuffs are made of a felt lining and leather material. There is high quality stitching and rounding of the edges. The ankle cuffs internal diameter goes from 7" to 12".