plain rail

plain rail

In a double-hung window, a meeting rail having the same thickness as other members of the frame of the sash.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Each COP Kit includes COP/Continuous Optics Platform (upper receiver/rail), forward assist, port door rod and cover, barrel nut, two center inserts, three Picatinny rails, three plain rails, 18 screws and an Allen wrench.