Browning rings are machined from aircraft grade alloy giving you a precision lightweight high-strength optic mounting solution for your hunting rifle. These are ultra-rigid vertically split rings use oversize hardware for extra strength and ease of installation. Sizing includes standard Intermediate and High rings are available for both 1 and 30mm diameter scopes - Compatible with the two-piece Scope Bases for A-Bolt BAR BLR and the X-Lock bases for X-Bolt rifles. - Standard (.300) For scopes with an objective up to 44mm and a standard barrel contour - Intermediate (.400) For scopes with an objective up to 50mm and a standard barrel contour - High (.500) For scopes with an objective up to 56mm and a standard barrel contour