Holosun Open-Emitter Red Dot Sight

From the Amazon Listing

• HOLOSUN RED DOT SIGHT - The HS407C X2 is an open reflex sight designed for full-sized pistol applications; It provides a large field of view that will help you increase accuracy and quickly acquire targets; This handgun sight features Lock Mode that locks the buttons preventing inadvertent setting changes
• HIGH PERFORMANCE - The HS407C X2 pistol sight features Holosun's Red Super LED with up to 50k hour battery life, Solar Failsafe, and precision 2MOA dot; The durable housing is made from 7075 Aluminum, uses an industry standard footprint, and houses the 1632 battery in a side-mounted tray for easy replacement when needed
• SHAKE AWAKE TECHNOLOGY - Extends battery life by deactivating the optic's LED while not in use; Shake Awake offers settings from 10 minutes to 12 hours depending on the model and can be deactivated altogether if preferred; The slightest touch of the optic instantly reactivates the LED so your Holosun reflex sight for pistol is ready when needed
• SOLAR FAILSAFE - If your battery fails, this red dot sight for pistol has a backup power source when natural or artificial light is available; Solar Failsafe is activated while in Auto Mode where reticle intensity is automatically adjusted: in brighter conditions, you have a brighter reticle and in lower-light conditions, the reticle will step down in intensity to match any lighting conditions
• SPECIFICATION - Reticle: Red 2MOA Dot Light Wavelength: 650nm; Magnification: 1x; Parallax Free & Unlimited Eye Relief; Power Source: Solar & Battery; Battery Type: CR1632; Battery Life (Hours): 50000; Brightness Setting: 10 DL & 2 NV; Window Size: 0.63x0.91; Housing Material: 7075 T6 Aluminum; Surface Finish: Anodize; Adjustment per Click: 1 MOA; W&E Travel Range: ±50 MOA