This is the CMC Products 1911 .45 ACP 8 Round Railed Power Magazine with Pad.

Since the Railed Power Mag by Chip McCormick was first introduced, these have quickly been known as some of the toughest 1911 magazines on the market. Its improved tolerance stainless steel USGI-style tube comes with enhanced feed lips. The stainless steel construction holds up to 10 rounds of .45ACP ammunition. And no more guessing how many rounds are left – there are witness holes on the right and left side of the magazine. Lastly, this 1911 Railed Power Mag comes with the impact-resistant polymer baseplate. Pick up a few of the Chip McCormick 1911 Railed Power .45ACP 8 RD Magazine w/ Pad from The Mag Shack.