It is one of the most reliable power connectors that they try to use on power batteries. These specific connectors are used on Li-Po batteries for copters.
An analog for XT-60. It has various options for simplifying disconnection.
Connectors of this type are often used for balancing individual elements in an assembly of several lithium-polymer (Li-Pol), lithium-ion (Li-ion), or lithium-phosphate (LiFePO4) batteries. Similar connectors with various numbers of pins are installed in most modern chargers for balancing the lithium cells during charging. This connector may be used together with a buzzer (beeper) for monitoring battery charge.
There is a great variety of Gold bullet pin connectors. Connectors of this type may have different diameters and size. The most widespread connectors are those with the diameter of 2 mm, 3 mm, and 4 mm. They are often used for solderless connections on PDB and motors.