This is an interesting product that will soon be released under the Amoeba brand of Ares Airsoft. Calling it the Amoeba Diversifying Handguard System, you can reconfigure the lower part of your handguard with these handstop, foregrip, and even attach a tactical light to it. According to Ares airsoft this can fit M4 AEGs and GBBs, and you can combine the different components to fit your requirements.