This is the Spektrum 6inch IC3 Battery to IC2 Device Adapter (SPMXCA320).

The Spektrum 6" IC3 Battery to IC2 Device SMART Battery Adapter Cable allows you to connect batteries with an IC2 or EC2 connector to an IC3 connector equipped Spektrum Smart device. This adapter features a male bullet/female housing IC2 connector, combined with a female bullet/male housing IC3 connector, that is joined with 6"/152.4mm long 18awg wire.