Review on Inflatable Pneumatic Hydraulic Test Plug - Safe-T-Seal TP123, 1.25-3 Inch, for Air or Water by Mark Green

Works as it should. As others have said, it's not found in big stores, but it's essential if you need to check your shower tray for leaks like I do. As for checking, where it bursts and "might mess up your tubes and hurt you," that's what happens when you inflate it outside the tube. Same principle if you inflate a bicycle tire tube from the outside of the tire. Without an external restraint (pipe) it will not reach pressure without buckling and bursting. Only a small amount of air was needed inside the 2" tube to reach a pressure of 35psi (maximum for a tube of this diameter). Read the directions and if you feel you should test it on a bench, place it in a piece of pipe.