PRi 6.8mm SPC waffle magazines with push button floor plate are constructed of butt welded steel halves to create the best internal volume for the magazine. We use Magpul anti-tilt follower with spring and push button floor plate allows for magazine to be quickly disassembled for cleaning. The 10 round magazine is 3.7" in length.  Hangs out of bottom of magazine well .9" at the rear.
This is newer design, we have removed the Waffling from the outer edges of the magazine to quiet down the magazine and reduce follower drag. 

Magazine also works for the .224 Valkyrie.