The CTA Manufacturing 18mm Magnetic Spark Plug Skt. with Swivel - Motorcycle, No. 7290, is designed for use for installation and removal of 18mm spark plugs found on street touring motorcycles, street sport motorcycles, off-road motorcycles, street cruiser motorcycles, snowmobiles, utility vehicles, all-terrain vehicles, street motor scooters, and marine applications. Its stubby design along with swivel action allows access into tight locations and its magnetic insert secures spark plug in place while in use. It's 18mm by 6-pt with a drive size of 3/8”.