Replacement Upper Guide heads for various MRP Chainguides. Please note, the bolt and slider nut are not included with the upper guide head and are sold separately. TR and TR2 Upper Guides are not interchangeable. Please refer to the info below to determine which upper guide you need. The HD and HD2 Upper Guides are interchangeable (same mounting style is used for both). G3, G4, and first generation SXg's came with the HD Upper Guide. G5 and current generation SXg's come with the HD2 Upper Guide.