Sampling Tube Finish Steel Duct Mounting Depth (In.) 5/8 in Height (In.) 5/8 in Length (In.) 30 in Tube Length (Ft.) 2 1/2 ft Width (In.) 5/8 in Duct Width (Ft.) 1 to 3 ft Standards UL Includes Notched Sampling Tube For Use With SL and RT Series Smoke Detectors