Killer Instinct Killertech broadheads brings strength, accuracy and deadly performance to crossbow hunting. Forget o-rings, springs and clips, the patent pending Speedlock system works on crossbows well over 500 fps without concern of premature deployment. The stainless blades are 50% thicker than average expandable broadheads giving them fantastic durability and strength on all big game species. FeaturesSpeed-Lok blade retention systemAircraft grade aluminum ferrule with stainless steel tipHeavy Duty 420 Stainless Steel bladesPerfectly balanced & spin tested for field point accuracy