The bsa sweet scopes use trajectory compensation technology that was originally designed for military sniper.They feature a quick change turret system specially calibrated for multiple grain weights for the calibers:.17hmr,.22lr,.223,.243,.270.The bsa sweet 22 ao compact is designed for the ruger 10/22 and other small-frame.22 rifles.It features a long eye relief for comfortable viewing, an adjustable objective, as well as the preferred 30/30 reticle.It comes standard with 2pc dovetail rings and fully coated anti-reflective lenses all in a one-piece aluminum housing. Adj Size: .25 MOA Magnification: 3-9x Objective: 40mm AO Field Of View: 34.20-11.50 ft @ 100 yds Eye Relief: 3 Tube Diameter: 1 Length: 12.13 Weight: 21.80 oz Reticle: 30/30 Duplex Parallax Adjustment: 7.5 yds-Infinity Parallax Adjustment: 7.5yds-Infinity Proofs: Waterproof, Fogproof, Shockproof Coating Type: Waterproof, Fogproof, Shockproof Optic Coating: Fully Coated Optic Coating: Fully Coated