The Gas Blowback Rifles are becoming the most popular system in airsoft market. Therefore, VFC, GHK, WE-Tech, G&P, VIPER, or even Tokyo Marui are having their own spec. for building their own Rifles, and most of the magazines are not compatible to use. Please be caution and make sure you are knowing which brand you going to buy for those magazines. and SIXmm will list them very clearly for our customer how to true or find the right magazine. Check the details down below.