Weaver Thumb-Nut Riser Rail The Weaver Thumb-Nut Riser Rail is designed to provide the optimal mounting height for optics on flat-top AR-style rifles. With its robust construction and user-friendly design, this riser rail ensures reliable performance and easy adjustments, making it an essential accessory for AR enthusiasts. Key Features: Optimal Height: Perfect for mounting optics, ensuring comfortable eye alignment on flat-top AR-style rifles. Durable Construction: Made from aircraft-grade aluminum, offering exceptional strength while reducing weight. Quick Adjustments: Features thumb-nut bolts for fast and effortless installation or removal without additional tools. Country of origin, China Weaver Recommended Torque Specs 6-48 Screws: 15 in lbs 8-40 Screws: 18 in lbs Instruction Manual