The No 503ATD Metal Air Tite Starting Collar with Damper is available in 12 sizes from 4 in through 20 in. Air Tite series starting collars have a gasketed flange to ensure the best possible sealing at the joint.
M&M Starting Collar, Round Air-Tite, 14 in, 5-1/4 in Length, Steel, Galvanized, Domestic