twist handle waist drain sink opening 3-1/2″ drain outlet 2″ nps face flange 4-3/8″ od actual dimension of the top is 4-3/8″ current inventory does not have an overflow outlet. we will be out of the multi-use twist drain untill later in this year 2014. you can substitute a lever handle drain # 56-1376.. which includes the overflow outlet if needed.