Abstract: A drain assembly which improves on the durability, economy and ease of manufacture and maintenance of previous drain assemblies. The drain assembly has a cartridge that threads onto a drain body. A spud or stopper slides up and down along the cartridge to open or close a drain. The improvement lies in a series of flexible structures extending outwardly from the cartridge to generate friction against the inner wall of the spud, holding the spud in the open of closed position. These structures may be finlike structures, bowlike structures, or both. The cartridge with the finlike structures and bowlike structures may be formed of a single piece of flexible plastic.