Permanent Cross-Slot Stability.

Steel rings that are based on the proven cross-slot design.

Uses the Leupold® QRW™ bases or any other Picatinny-style mounting rails. 

Very fine Weaver rings, but perhaops a bit more tricky to work with, as far as mounting the scope.

Alloy rings are machined from a single piece of aircraft-grade aluminum so they are incredibly strong, yet lightweight

Also available in good 'ol steel