Thank you for viewing. The Wise Grip is a trombone hand grip designed based on ergonomics. It disperses the weight that burdens the left hand, allowing for stable holding. A stable left hand leads to a stable embouchure and comfortable slide action. Made of resin. The large size is mainly for large-bore trombones (cannot be attached to narrow slides or instruments with curved inner slide handles). Compatible with K&H (large bore), Thein (large bore), Stomvi (large bore), Bach (42B, 50B), C.G. Conn (8H, 88H, 60H, 62H, 70H, 72H, 110H, 112H), Shires (large bore), Edwards (large bore), Getzen (large bore, excluding narrow slides), Jupiter (large bore), XO (large bore), and Yamaha Xeno (excluding narrow slides). I used it for about six months, but it's in excellent condition with no scratches or signs of use. Thank you.