This is the Magpul PMAG 10 7.62 AC – AICS Short Action 7.62x51mm magazine designed for the SIG Cross rifle, also fits AICS other short action rifles.
The key difference vs the standard PMAG 10 AC is a special follower which has a feed ramp built into it. Allowing single round loading through the ejection port without needing to remove the mag.
Made from Magpul's usual ultra tough polymer it is fully strippable for cleaning.
Will not fit Tikka T3 or Browning X-Bolt actions mounted on AICS chassis without modification of the feed lips, please use steel magazines.