Type 11a is a variation of our Type 11 T-rail suspension, ideal for low ceilings. It is supreme for straight sections of D shaped ducts and differs from Type 11 in that it is a keter type bulb edge, which is pulled into place, creating a beautiful, uniform suspension with a nice closing. The T-rail, so named because it looks like a T in the cross section, is made of anodized aluminum, making it an excellent choice for corrosive environments. Two T-rails are fixed to a hard ceiling and the duct is then suspended from the rails. The duct will have a keter type bulb edge at the 3 and 9 o’clock positions. The height of the bulb edge above the duct can be manufactured to specification.