Engineered with the revolutionary bullet-drop technology, these scopes are guaranteed to make you an extreme performer when it comes to the .17 Magnum Rimfire shooting. The scope’s elevation knob is precisely calculated to compensate for the elliptical drop of the .17 Magnum Rimfire with a 17 grain bullet. Once you complete the zeroing process at 100 yards, all you have to do is match the elevation turret indicator with 100yds marking on the knob. From this point, your trajectory can be compensated for any yards from 100 up to 300 yards simply by turning the elevation knob to the desired setting. Pre-calculated Trajectory compensation from 100 to 300 yards by turn of a dial. High Density Optical Glasses for crisp edge-to-edge clarity. Multi-coated optics for brighter images. Adjustable objective lens for parallax correction. 100% Waterproof, Fogproof & Shockproof.