Includes (8) QL78C Spark Plugs. Thread Size: 14mm, Seat Type: Gasket, Resistor Type: Inductive, Reach: 12.7mm (1/2"). Hex Size: 13/16" (21mm), Terminal Type: Solid, Gap:.030" (0.75mm). Material: Nickel, Type: Standard, Size: 2.5mm, Projection: Non-Projected. Conventional spark plug with nickel alloy electrodes. Copper core center electrode allows for increased conductivity and heat control. . Compatible with the Following: Autolite: 2653, 4092, 411, 421, Bosch: W3AC, WR4AC, Champion: RL78, RL78C, XL78, NGK: 3579, 4322, 4915, 6715, BR7HS, BR8HCS10, BR8HS, BR8HS-10, BR8HS10, BR8HV, BR9HS-10, BZ7HS-10, BZ7HS10, Torch: E7RC