Various taps can be mounted on the 2" S56X4 and 1x 3/4" S24x4 opening. Please note that the screw thread is different from steel drums. Plastic bondel drums have a coarse screw thread, steel bondel drums generally have a fine screw thread. Don't forget to order an adapter if you want to mount a tap on the barrel. We also advise you to order a barrel screw cap wrench for easy opening and closing.