This is the E-Flite EC3 Battery Connector, Female (2)

EC3 Battery Connectors are ideal power output connectors for electric applications. EC3 Battery connectors are available to match up with the EC3 Device connectors.

Features:
Capable of 60 continuous amps
Ergonomically pleasing and easy to grip
Protected to avoid shorting and reverse polarity
Superior technology suited to today's advanced applications
Connectors are factory-installed with ParkZoneŽ F-27C Stryker, E-flite PNP aircraft,
Designed with convenience and reliability in mind

Overview:
E-flite's high-quality EC3 connectors and leads should be a staple for every workbench. EC3 (E-flite Connector 3.5mm) connectors, leads with connectors, and accessories are perfect for electric power applications and work with any battery, charger, ESC, Power Meter, etc.

Requires:
EC3 Devise Connector, Male (EFLAEC301)