ARMED FORCES SERIES. Premium 2-1/4" diameter Black shift knob with embedded Unites States Navy emblem. Comprised of specially formulated high-impact polymer resin specifically designed to meet performance level torque and temperature requirements. This knob has a 16mm x 1.5 Brass master insert and comes with a threaded Brass adapter & jam nut in the size of your choice. Made in the USA. Factory Mustang shifters may require a Boot Retainer to complete the installation. Corvette thread sizes (9/16-18 & C6) may require up to 4 weeks for production and delivery If you are not completely satisfied with this item you may return it within 30 days for a full refund. 1 year limited warranty.