The Umarex EBOS is an inexpensive yet extremely enjoyable Full Auto BB machine gun. "EBOS" stands for Electronic Burst Of Steel and the EBOS name does not let you down. The Umarex EBOS uses an electric motor combined with an 88 gram CO2 cartridge to hurls BB's at speeds up to 540 fps. On a brand new CO2 you can actually feel the recoil from the high pressure CO2 blast. The EBOS is a good alternative to someone considering the Baikal Drozd but perhaps on a bit of a tighter budget.