Handcuff Keys from Police & Law Enforcement Supply / Tactical Division of U.S. Water Rescue located in Billings, MT. Handcuff keys are of a standard design and are compatible with all standard series handcuffs. All keys are made of heat treated stainless steel and are designed to provide an indefinite period of service. Because of the high grade material and craftsmanship employed, it is possible and practical for us to offer an unlimited lifetime guarantee.