I am trying to locate a bathroom sink drain fixture that closes by pushing down on the stopper itself and opens by pushing on the stopper again (not the kind that uses a pull-rod on the faucet). I have found this type of drain for bathtubs, but cannot find a source for sinks. I know for a fact they exist, because I have a St. Thomas above-counter sink that had this type of drain included with it. Can anyone give me a source lead? Thanks.