extension bolt

extension bolt

[ik′sten·chən ‚bōlt]
(design engineering)
A vertical bolt that can be slid into place by a long extension rod; used at the top of doors.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

extension flush bolt

extension flush bolt
A type of flush bolt; bolt head is connected to the operating mechanism by a rod inserted through a hole bored in the door.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.