This is the New NHX 1/8 Side Mount Clip-on Motor Heatsink with High-Speed Twin Cooling Fan. Each fan is 40x40mm with JST connectors ready to plug into your receiver port.

Features:
For: 1/8 Motors with around 42mm diameter
Material: Aluminum Heatsink with plastic Fan housing
Input Voltage: 6.0-8.4v
Fan Dimensions : 40x40x10mm
Fan Max Speed: 16000 RPM
Connector: JST

Note: The motor shown is for illustration purposes only.