Fit Hole Size: 1-1/2' to 1-5/8' (38mm-41mm). Replacement for Rubber Expansion Plug/Rubber Freeze Plug/Exhaust Pressure Test Plug Easy Installation: A wrench is the only tool required to install the expansion plug. Rubber freeze plug resists heat, anti freeze, oil and rust inhibitors. Package Includes: 4pcs x Rubber Expansion Plug