Arlington's small diameter sconce box for retrofit is an ideal solution for mounting a sconce quickly and securely. Measuring 3-1/4" diameter, most sconce light canopies cover the box completely for an invisible installation. It has a volume of 6.8 cubic inches and is rated for up to a 3lb sconce. Our sconce box ships ready to use, no loose parts. Fits double drywall or walls up to 1.90" thick.