The AUTOLITE AR51 Set (4pcs) Copper Core Spark Plugs Non-Resistor Gasket Seat 14mm x 1,25 Thread are a set of spark plugs that are made of copper and have a non-resistor gasket seat These plugs are designed to work with engines that use 14mm x 1,25 thread pistons AUTOLITE AR51 Set (4pcs) Copper Core Spark Plugs Non-Resistor Gasket Seat 14mm x 125 Thread