The NAP Dark Knight is a hybrid fixed/mechanical head with a single, swiveling blade on the front. The main blade is held in place by NAP's spring clips that they use in the Spitfire/Killzone heads so it won't move around in flight. On impact it swivels back and forth to help with penetration around bone. Just like the Spitfire DoubleCross it has bleeder blades on the opposite sides that give an extra 1 1/8" cut. However they did improve those bleeders and moved the tabs further up on the ferrule so they catch and begin to open right as the main blade is impacting the animal. The DoubleCross occasionally had some issues getting enough tissue to catch those tabs open after the main blades opened the entry wound.