Stereo zender, F to F, keystone jack wall plate module, This module is designed to work with keystone jack wall plate, color=white. Keystone jacks are a family of standardized snap-in modules for mounting a variety of low-voltage electrical jacks or optical connectors into a keystone wall plate, faceplate, or surface-mount box. Keystone jacks have a rectangular face of 14.5mm wide by 16.0mm high and are held in place with flexible tabs. This allows them to be snapped into a mounting plate with similar sized rectangular holes, called ports. All keystones, regardless of the type of jack, are interchangeable. Keystone jacks are desined to work with many different types of electrical jacks in one plate or panel without requiring customized manufacturing. Some keystones use a pass-through type connector, where there is a jack on both the front face as well as the rear side. Others only have a jack on the front and employ a different mechanism for hard-wiring signal cables to the rear.