"Simple, fast, effective-the push-button design of the Vortex Optics VMX-3T engages and disengages the flip-mount, allowing the magnifier to lock in place. The result, 3x magnified or unmagnified views at will. Optics are fully multi-coated for optimal light transmission. Lightweight and tough; hard-coat-anodized machined-aluminum construction ensures durability. Internally nitrogen purged for reliable waterproof/fogproof performance. Ultimate magnified versatility for virtually any AR-height red dot sight.|Fully Multi-Coated Lenses: Increase light transmission with multiple anti-reflective coatings on all air-to-glass surfaces|Waterproof: O-ring seals prevent moisture, dust and debris from getting inside the tube for reliable performance in all environments|Fogproof: Barrels are filled with nitrogen gas to inhibit internal fogging"