Wheeler Engineering Anti-Cant Indicator, 30mm Crafted from machined aluminum with an anodized finish Indicates precise, repeatable level gun position Increases accuracy by insuring proper gun alignment, which is critical for turret adjustment and hold over for bullet drop compensation Easy-to-view from shooting position Attaches to scope, folds in when not in use Precision machined aluminum with anodized finish Keeping your scope perfectly aligned is critical to long-range accuracy. Canting your scope, even just a couple of degrees, can cause error in point of impact. With modern Drop-Compensating scopes, an Anti-Cant Indicator is a necessity. If your gun isn't aligned correctly dialing up the turrets or using hold-over marks, will just throw your shot off. This error can easily be enough to cause misses. The Wheeler Anti-Cant Indicator ensures that your rifle is always held near perfectly vertical, eliminating any chance for cant-error to cause a miss. The Indicator reveals precise, repeatable level gun position and increases accuracy by insuring proper gun alignment - critical for turret adjustment and hold over for bullet drop compensation Easy-to-view from your shooting position, the Indicator attaches to your scope and folds in when not in use. Constructed from precision-machined aluminum with anodized finish.