ZAK Tool products are designed especially for Police and Fire agencies. Made in the U.S.A. of the highest quality materials, their products are built to last. For example, their 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 them to offer an unlimited lifetime guarantee.