The next generation ultra-compact micro red dot sight optimized for every day carry on slimline pistol slides. No plastic body or polymer lens for us, only hard coated 7075 aluminum and multi-coated glass here. Sentinel-A truly never sleeps. A photosensitive sensor on the left side of the scope body provides a bright dot relative to ambient light in all conditions, day or night. There are no manual controls at all, no Shake 'N Wake no way for Sentinel-A to be accidentally shut off, ever. Install the CR2032 battery underneath Sentinel-A and you're good to go for two years straight. Sentinel will fit Glock 43X and Glock 48 MOS, Sig P365XL, Springfield Hellcat OSP, Can Mfg: Swampfox Optics