I have Pmags (10) in 30 rounds and 75 rounds, they work perfectly in my ICS M4, KWA M4 and my Classic Army M15A4. They work in my VFC Scar now that I modified the magwell. The magpul s with a window that lets you see the bullets are bigger and probably wont work in your ICS. I like Pmags, they are a good deal and look great but you cant fit 2 of them in the same mag pouch. Never had any problems in the last two years (including winter) with the 30 rounds mags, the 75 round mags need a little tlc once in a while.
http://shop.ehobbyasia.com/magazines...rab-10pcs.html
http://www.airsoftparts.ca/store2/in...oducts_id=1393