Monument Drain Testing Plugs are durable, quality flexible drain plug for the plugging of drains and pipes. This plug is easy to use and are available in various sizes. Fitted with removable top caps and rubber rings. These plugs are easy to use just place in the pipe end that is being repaired or replaced and simply turn the wing nut knob, this will depress the rubber cone, this will make it expand to seal pipe or tube end with a water tight seal. The Monument MON1377 1377W Drain Testing Plug comes with the following specifications Size 75mm (3 inch). Capable of sealing against pressures of up to 2.24 bar / 33 psi.