Cim-Tek's heavy-duty cast-iron mounting adaptor (commonly known as a filter head) is made to withstand the harsh elements and last for years. The adaptor has a 1" NPT inlet/outlet and a 1 3/8"-12 nose thread (where the filter screws on). Use with 200AE, 250AE, and 260AE series filters. 1" x 1" x 1"