This is a purpose-built 12v li-po battery (nominal 11.1), 3000mah, if features 2 barrel plugs 2.1mm outer and 0.7mnm inner diameter in order to power both sunans boosters (2.4GHz and 5.8GHz) it's very tiny and has a on-off switch, it will give a reliable 2 hour autonomy powering the sunhans 2.5w booster. alone or 1 hour+ powering both 5.8 and 2.4ghz boosters. It was selected for light weight (115gr) in order to be used on the transmitter. This means that it needs to be charged after 2 flights. The included charger provides 1A charging current this means that it will take 3 hours to charge it from completely empty and in most cases a couple of hours to top-up.
These laser cut 3mm cell cast acrylic pieces are designed to carry 2 extra batteries strapped to the bottom. 8