MACHINED ALUMINUM CONSTRUCTION - Built strong from machined aluminum to withstand high FPS crossbow demands. SPRING-LOADED ROLLER SYSTEM - Smooth, spring-loaded rollers reduce friction for accurate crossbow arrow flight. HIGH FPS PERFORMANCE READY - Designed to handle the demands of high speed RAVIN crossbows without failure. COMPATIBILITY RESTRICTIONS - Not compatible with R18, R470, or R500 Series crossbows, fits other RAVIN models. RAVIN SERVICE DEPARTMENT AVAILABLE - Available through RAVIN Service Department or your local dealer for proper installation.