Single Gang, Old Work Box, 20 CUIN, 4-1/8" x 2-5/16" x 3-5/8" Deep, For Large Wiring Devices, Extra Wire Capacity, Lightweight, High Impact PVC Construction, For Use in Existing Construction Remodeling Work box Fits Into Standard 2" x 4" Constructed Wall, UL Listed For Fire Resistance. Designed for use with nonmetallic sheathed cable. Carlon(TM) Zip Box(TM) Blue™ boxes make fast work of any residential or light commercial application. The contractor's choice for easy installation.