Fox Airsoft presents the BTS Mod 3 AEG from Echo1 USA Airsoft. This model is compatible with both straight and curved MP5-style magazines, as well as SG/SOB series magazines. It features a drop-free magwell and a CNC Free Floating MLOK handguard. The BTS Mod 3 AEG is equipped with a Version 2 gearbox with a quick-change spring system. The QBS quick change allows for a spring change without the need for receiver disassembly.