Part No. MTC-300BB12
BestinClass Three Cubic Foot Back Box for 12 Models. Rectangular with ExtraThick 16 Gauge Metal and Heavy Duty MDF Reinforcement on Top and Side Panels.Fits Control 321C, 321CT, 322C, 322CT 321CS. 23.1 x 18.2 20 Incl. Side Tabs x 12.8 Deep. NOW UL LISTED Priced as one pack; one pack contains 2 Pieces