●SP 877-323 Piston Driver: Aluminum is crimped into the unilok grooves of the shaft to prevent unscrewing. Hardened steel lock tite and micro-mechanically locked piston driver interface. Guaranteed never to unscrew. ●SP 878-303 Piston Bumper: Precision machined, virgin high density yellow color plastic framer bumper. ●SP 884-570 Steel Magazine: Fits Hitachi NR83A / A2.