Cover snaps onto base - no screws required. Cover has twistouts on all sides. Rectangular KO in base for extenstion to wall box. Used with 2700, 2800, 2900 and NM2000 Series Raceways. 4 3/4" L x 4 7/8" W x 1 3/4" D (121mm L x 124mm W x 44mm D). 2-Gang.