The Best Test Tee Mechanical Test Plug in the market and this Test Plug comes with the water fill feature which gives you the option to fill with air or water! American Made Test Tee Mechanical Plugs with high quality material! The mechanical devices that holds the ttmp in place is the unique two-stage mechanical locking mechanism; lock tight test positioned drain position. Pin design permits plug to be pad locked. Maximizing user safety, no air requirement allows fail safe test setup. Replaceable rubber pads available.