Watco 38516-BN Push Pull Replacement Stopper with 5/16 & 3/8 Pins, Brushed Nickel Theft-resistant, brass stopper - designed for heavy-duty use Replaceable, drip-proof Buna-n-seal - patents: U.S.A Pat. No. 4,720,877 Operation: push down to close. Pull to open. No stopper rotation required