KWA Central reports on the "KMAG" 120 round Polymer Mid-Capacity Magazines that have an uncanny resemblance to the PMAGs and EMAGs according to their blog post. According to them, it’s easy to takedown the magazine for cleaning and maintenance and you they are available in boxes of 6 for US$60 per box (that'll be US$10.00 per magazine). The quality looks really good and if you're not mindful of the big KWA letters on the side, then you might want these magazines for milsim games.

More photos and details of the magazine here.