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. 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.