1 1/2 inch Fitting Winterizing Pressure Test Plug made by Aladdin 800-10 Winterizing Test Plugs Featuring The Easy Grip Knob. Get ready for winter and keep pipes from freezing and bursting. The winterizing plugs are made with soft rubber which allows for maximum expansion. They provide a tight seal even during expansion and contraction due to severe temperatures. They feature a tighter contour to make installation quick and easy. The Easy-Grip, No-Slip (EGNS)knob has specifically designed to make hand tightening easier and less painful on the fingers. The larger grip also excepts a 1socket making installation and removal a snap. TESTING: Winterizing Plugs are ideal for testing applications. Once installed the system can be pressurized and tested for leaks.