"X" marks the spot. Weaver styling combined with the X-Lock's four-screws-per-base design gives you a rock solid foundation for your scope. Lightweight, strong and solid. Most people consider Weaver style bases the industry standard for hunting rifles. Made from high quality aircraft grade alloy, these bases will work with Browning rings, or just about any other Weaver-style rings you want to mount on them. But these are for the X-Bolt with X-Lock only.