This is the Castle Creations X Series Sensor Harness.
FEATURES: Allows sensored brushless motors to be run with sensored-capable Mamba X-Series ESCs Easy to install; remove sensor dust cover from ESC, plug harness into ESC and plug sensor wire of motor into harness
INCLUDES: X Series Sensor Harness
SPECS: Length: 1.3" (34mm) not including connectors