Hubbell-Raco 911-1 4" Square Red Alarm Box, 1/2" & 3/4" KOs, Welded, Metallic

FM Bracket, 4" Square, Red Alarm Box, Welded, Metallic. Depth: 3-1/2". Side Knockouts(10) 1/2" & 3/4" (concentric). Bottom Knockouts: (4) 1/2" & 3/4" (concentric). End Knockouts: (8) KOs. Cubic Inches: 40.5". UL Listed for Use in 2 Hour Fire Rated Walls.