Monstrum R02 Ultra Compact Red Dot Sight with Light Sensor Auto Adjustment and 1 inch Picatinny Riser Mount Ultra lightweight reflex sight suitable for use with a variety of pistols and firearms Precision 3 MOA dot with easily adjustable windage and elevation settings Light sensitive red dot automatically illuminates upon exposure to light and auto-adjusts according to light environment Mounts directly to any Picatinny rail or on top of a 1 inch Picatinny riser mount (included with purchase) Flexible eye relief, suitable for almost any shooter or firearm