This is a Weaver Ring known as the Tactical, model 99693.
Weaver's popular Six Hole Tactical Rings just got the Picatinny treatment. These new rings feature the same six screws for max security and clamping pressure but get serious upgrades for LE and military use. An improved Picatinny crossbolt design (from Weaver to Picatinny spec)" Type III hard coat anodized finish" no strip/slip Torx screws and an increased number of height options make these new 6-hole rings the go-to mounts for all Tactical Precision rifles.
Improved crossbolt from WeaverÂ® to Picatinny spec
Six screws for extra security
Increase height options for broad applications and firearms