STAINLESS STEEL THUMB-CUFFS Double Locking Handcuffs for Thumbs Thumbcuffs Cuffs. A pair of Good Quality Stainless Steel Professional Police Thumb-Cuffs. It can be used on their own or in conjunction with handcuffs for an added level of security. Zinc-plated steel thumbcuffs from Russia. They are large thumbcuffs with an unusual shape. Both sides open simultaneously by turning key once. A single double lock pin at the top activates double locks with the end of the key. Both single and double locks release by turning key one direction. Weigh 4.8 oz. One key included.