The RDP Galvanized Flue Plug with Crimp caps pipes with undersized crimped edges. It installs securely inside the pipe and fits inside diameters (ID) ranging from 3 to 18 inches. This Flue Plug is quality constructed from heavy-duty 28 gauge galvanized steel and is designed to cap off or terminate the end of a pipe. Please verify your pipe measurements before ordering to ensure proper fit.