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 Sampling Tube, For Use With SM Series Smoke Detectors