The Buffer Ring 86715463 cushions the piston’s impact in HC25 Hydraulic Rock Drills, reducing vibration and noise while extending component life. Generic buffer rings use low-density rubber that loses elasticity within 500-600 hours, increasing impact stress. This OEM ring is made from high-density polyurethane elastomer with ≥70% impact absorption, maintaining its cushioning effect over 800 hours. It fits precisely in the piston’s buffer groove, reducing vibration transmission to the drill frame and requiring mandatory replacement after 800 hours.