The redesigned X-Treme, now with the exclusive NC (No Collar) blade retention system eliminates the need for a Shock Collar, dental band or O-ring. Taking verse from the original X-Treme, the new-for-2020 2-blade design is centered around a 1.425-inch long high-strength 6061-T6 aircraft grade aluminum ferrule whose two. 039-inch thick blades instantly deploy to an enormous 2.3 inches upon impact.