The 507C-X2 is an open reflex sight designed for handgun applications. Features Holosun&&';;s Multiple Reticle System giving the user three reticle options. Shake Awake technology activates the LED at the slightest detection of movement and deactivates the LED during periods of motionless. The 507C-X2 has 10 daytime brightness levels and 2 night-vision compatible levels. 50,000 hours of battery life on setting 6 means you won&&';;t be changing batteries often, but when you do need a replacement, the convenient battery tray allows the user to swap batteries without removing the optic from the slide. The 507C-X2 also includes Holosun&&';;s Solar Failsafe technology to power your optic in the event of battery drain or failure. This optic is parallax-free and has unlimited eye relief. The Holosun 507K-X2 is IP67 waterpoof rated.