The industry-standard JST "RCY" mini connector, with soft silicone wires and pre-tinned ends. This is the male (pins) plug that connects to the majority of small hobby-grade lithium battery packs. It is also know as the Tamiya "BEC" connector.
Note that there is sometimes confusion as to which "gender" these connectors are! Although the shrouded housing may suggest that this is the "female" version, it's actually the male, since the gender is determined by the metal pins inside, not the housing. (this connector has male pins, the common battery-side has female metal "sockets")
This connector is keyed, making it nearly impossible to insert backwards, an important feature on devices that don't have power input protection diodes!