Abstract: A clasp lock whose clasp is a homogeneous one-piece U-shaped metallic casting having a rigid leg, a resilient leg and a rigid web which is integral with one end portion of the rigid leg as well as with one end portion of the resilient leg and is first to enter the chamber of the receptacle when the clasp is inserted through the opening in the front wall of the receptacle. The cross-sectional area of one or more parts of the intermediate portion of the resilient leg diminishes gradually or abruptly in a direction from one toward the other end portion of such leg.