RedWolf Airsoft now have G&P's Ready-Mag, the company's take on the "Redi-Mag" with some minor design difference, in stock. The photo used above is Xmattedgex Custom KJW M4 with Ready Mag painted in tan and was posted at the Airsoft Canada forums... "Clamps onto M16 based rifles for storing your spare magazine, many airsofters use the ReadyMag system to store an battery within a gutted magazine. Best for powered-up SR16s. Note that this unit is designed for airsoft and will not fit a real steel M16 series rifle properly.

This unit does not come with an extra magazine, which you need to purchase separately.