Tang presents two PDWs from Echo1 USA Airsoft, the BTS Mod 2 and Mod 3 PDW AEGs distributed by Jag Precision... "The Echo1 BTS series airsoft rifles are full metal AEG (automatic electric guns) that have what airsoft players what. It has plenty of standard features for the mission but you are not locked behind proprietary parts or design that prevent you from upgrading it the way YOU like.