Virtually indestructible light emitting diode has no filament to burn out or break; lasts for thousands of hours. Precision reflector creates smooth beam without spots or rings. Rugged aerospace-grade aluminum body, Type II anodized in glossy black. Coated Pyrex window protects LED and reflector while maximizing light transmission. O-ring sealed; weatherproof. Tailcap switch: press for momentary-on, twist for constant-on. Patented switch lockout prevents accidental activation.