Spark plug, Autolite Copper 437, hot heat range, power tip, non-resistor; 14mm thread diameter, 7/16 inch reach, 13/16 inch hex. For tractors 1939 to 1950 with front mount distributor. Used in 309786 and 309787 tune-up kits. Champion cross reference: H14Y, H18Y. 4-pack.