173 Lumens + 209L boost feature. Multi-level light easily adapts to changing conditions. Battery saving lock-out prevents accidental power on. Dual output: spot for long range, flood for wide proximity lighting. Rear mounted external battery for extra-long runtime. Regulated circuit delivers consistent brightness throughout the useable life of the battery. Red Halo low-lumen mode designed to enhance sight without compromising natural night vision. Battery saving lock-out prevents accidental battery use. Top-quality Cree LEDs.