This is the Surefire 6PX Pro Light Dual-Output LED Flashlight 6PX-B-BK

Features:

• Virtually indestructible LED emitter regulated to maximize light output and runtime
• Two output levels—high for maximum light, low for extended runtime
• Precision micro-textured reflector creates smooth, optimized beam
• Tough polycarbonate window resists impact
• High-strength aerospace aluminum body, Mil-Spec hard-anodized for extreme durability
• Dual-output tailcap click switch—press for momentary-on low, click for constant-on low, return to off then press or click again for high
• Weatherproof—O-ring and gasket sealed
• Includes high-energy 123A batteries with 10-year shelf life

The 6PX Pro's high-efficiency LED—virtually immune to failure since there's no filament to burn out or break—provides two light output levels: a brilliant, penetrating, perfectly pre-focused 200-lumen beam, and a 15-lumen low-output setting that lets you greatly extend the runtime per set of batteries, an invaluable option when you find yourself miles from civilization.