Official video from Tokyo Marui as Deka walks us through the features of the SG553 Plus AEG... "Introducing the SG553 Plus, an electric gun that can use MS Li-Po batteries! The PLUS system (FET circuit) provides high safety and improved trigger response during semi-automatic firing. Based on the standard SIG552 Shields electric gun, the SG553 Plus has been upgraded both inside and out to a higher level of operability."