The 4612 Power Transfer Device channels electrical wiring from the door frame into the door itself. Designed for use with locks, exit devices, and more on doors hung with butt-type hinges. Provides a secure and unobtrusive means of channeling electrical wiring from the doorframe into the door itself, for powering electric strikes on the inactive leaf of a pair of doors, locks, exit devices, etc. Spring steel helix has internal diameter of approximate 5/16". This provides ample room for multiple wires of the low voltage type used with most electrical hardware. Suitable for any door hung with butt-type hinges, including continuous or pivots offset 3/4" [19.1 mm] or less. Not compatible with center-pivot doors. Particularly for out-swinging doors, a steel barrier fence offers extra protection against attack on the conduit by knives, shims, or other tools. Completely hidden when door is closed.