Overview Durable metal string retainers designed to stabilize string angle at the headstock, help maintain tuning stability, and reduce string wear. Includes two retainers in different sizes and two mounting screws for quick replacement or upgrade on electric guitars and similar instruments. Key features Material and color: Zinc alloy body with steel components, black finish for a discreet look. Sizes included: 1.06 x 1.10 x 1.10 cm and 1.70 x 0.50 x 0.50 cm. Inch equivalents: 0.42 x 0.43 x 0.43 in and 0.67 x 0.20 x 0.20 in. Package contents: 2 x guitar string retainers and 2 x screws ready for installation. Function: Roller style string trees guide strings at the headstock, maintain consistent break angle over the nut, and help stabilize tuning during playing and bending. Durability: Hardened zinc alloy and steel construction for long term use and resistance to deformation. Easy installation: Supplied screws and compact mounting size allow straightforward replacement of worn or broken string trees. Benefits Improved tuning stability by keeping proper string tension and angle. Reduced string abrasion and wear at the nut area, extending string life. Metal construction delivers greater durability than nonmetal parts and consistent performance over time. Compact black design fits discreetly on most electric guitar headstocks. Typical use scenarios a broken or worn string tree on an electric guitar to restore stable tuning and string alignment. Upgrade from plastic or low quality retainers to metal roller string trees to reduce string binding and tuning issues. Install on a custom or repaired headstock when building or modifying an electric guitar to achieve cleaner string path and lower maintenance. Compatibility and notes Suitable for most electric guitars and other instruments that use string trees or retainers on the headstock. Check mounting hole placement and clearance to ensure proper fit. Two different sizes provide options for various string spacing and headstock layouts.