I’m looking for the piece of hardware that’s located immediately below the sink drain that mixes overflow (from a tube) with the water going down the drain. Basically, a properly sized cylinder with a hole in the side(to accept the tube).
If this is a commercial sink then you need a Fisher or similar rotary waste with the overflow opening in it. The overflow should be 1″ tubing and therefore you will not get an independent piece that will work.