All the Pro Series Mechanicals are COMPOUND AND CROSSBOW approved for any set-up. They feature the New PRO TIP and Snap Cup design which holds all components in place for easy installation on your arrows. Super strong, razor sharp .035 stainless blades. No O rings , bands, or clips. Blades stay closed out of the fastest bows ands crossbows yet open smoothly on impact! CARNI-FOUR 4-BLADE - 4-blade, 1 x 1 mechanical with Staggered Blade Technology that will change the mechanical world forever! The instant the two longer 1 cut blades make contact and compress the internal spring, the two shorter 1 cut blades release and open with the touch of a hair! Giving you the largest 4-blade entrance hole on the market and an incredible square wound channel from start to finish!