GNB Liion 4000mAh is a pack of Liion 21700 cells in a 4S1P configuration. The battery is suitable for lightweight 5" or 4" drones and long distance flights. This battery combined with a lightweight 5" drone will offer 20+min of flight. The battery is assembled with Lishen cells. Minimum battery voltage is 2.5V per cell (10V total). However, it is recommended to leave a small reserve.