A detachable portable fastening device, having a shackle or bow adapted to be opened for engagement through a staple or the link of a chain. The bow or shackle, when locked, is secured in the case by means of a spring-activated pin(s) entering a notch(es) in the shackle. The lock may be opened by inserting and turning a key or keys, by key insertion only, or by a predetermined setting on the dial of a combination lock. For two or more padlocks which are keyed alike and/or master keyed, see padlock set.