These compensators are easily adapted to Osprey’s INDUSTRY LEADING Compact 3-9x42IRF/MDG Scope making them a class-leading optic for almost any situation. These are very easy to use by zeroing your weapon at 100yds and compensating by simply winding the knob counterclockwise to your distance marked on the turret. They come in .223/55gr , .308/168gr and 7.62x39/123gr. The Compact bullet drop compensators are backed by Osprey’s industry leading no-nonsense lifetime warranty.