This product is designed for 2x4 wood studs. 21 in. diameter wire shock absorbing wire tray Capacity: 100 lbs. Greased retaining spindle gives trouble-free service eliminating maintenance over long periods Spindle spring adjusts to desirable free spool Wire guide also serves as a carrying handle Designed for 14-2, 14-3, 12-2, 12-3 wire Rotational wire guide allow pulling in any direction Raised edges on wire trays prevent wire spill Eliminates twisting and kinking of wire Constructed of high grade steel, zinc, and aluminum