Abstract: An improved fastener is provided for mounting an object to a base, wherein the object has a threaded shaft extending through a hole in the base. The fastener includes a collar having a side wall, a first end with a threaded aperture for receipt on the shaft, and an open second end defining a cavity within the collar. A locknut received within the cavity of the collar has a first end with a threaded aperture therein for receipt on the shaft so as to cooperate with the collar in a double-nut arrangement. The second end of the locknut has a key recess therein for receiving a key socket or key wrench for tightening the locknut. The collar covers the locknut so as to prevent removal of the locknut and the collar without use of the key socket or key wrench.