The BSA Red Dot Sight is a wonderful lightweight sight for close quarter and medium range targets. This BSA Dot Sight is light enough for small caliber plinking on the range, yet durable enough for larger calibers used by hunters and law enforcement departments. You can adjust the brightness of the dot, depending on the brightness of your surroundings. The BSA Dot Sight offers faster target acquisition and more precise shooting in a wider field of view. With a 5/8" rail mount, the BSA Dot Sight is ideal for shotguns, rifles, pistols, bows and crossbows. This BSA Red Dot Sight measures 4.5" long x 2.2" wide x 6.3" wide and weighs 0.31 ounces. BSA 20mm 5-MOA Red Dot Sight: * 5/8" rail mount only * Object lens diameter: 20mm * Magnification: 1X * Field of view at 100 yds: 45 * Parallax setting: 50 yds * Click adjustment value: 1/4 * Adjustment range: 45-45 * Weight: 0.31 oz * Dimensions: 4.5"L x 2.2"W x 6.3"H * Model# RD20CP