Drum Tap in Cap This drum tap fits our 20L cubes and our 30L Cubes. It also works great on our Molasses Cubes. This tap will fit all drums and cubes with an opening diameter of 58mm. These are a fantastic solution for leak free storage, all you need to do is unscrew the lid and screw one of these on. Then tip the drum on its side and turn the tap to dispense. This tap has an inbuilt breather so it lets the air back into the drum as the liquid drains out. It saves you having to open the bung at the bottom.