A duct joiner for connecting an air duct to another duct or other part of an air conditioning system has a tubular neck portion, a retaining clip and a sealing ring both mounted on the neck portion. The retaining clip has a ring portion received in a groove in the outer surface of the neck portion and...http://www.google.com/patents/US5921592?utm_source=gb-gplus-sharePatent US5921592 - Duct joiner and retaining clip therefor
