Switch-Device Outlet Box Extensions (Metallic): Type - Nongangable; Material - Steel; Number of Gangs - 1; Box Height - in - 3-3/4; Box Width - in - 2; Box Depth - in - 2-1/2; Capacity - cu-in - 18.5; Clamps - NM Cable, Self-locking; Mounting Hardware - Positioning Tabs, External Nailing Provision