This is the Yeah Racing 40x40x10mm Tornado High Speed Cooling Fan in Black color. This fan features dual ball bearings and is great for motors, ESC's and multiple other applications. This fan is capable of use with a 2S LiPo (8.4V), but no higher.

Specifications:
Fan Size: 40x40x10mm
Operating voltage: 5-8.4V
Start-up voltage: 3V
Weight: 13.0g
Material: Plastic Blade and Frame Housing
Bearing: Dual ball
Shaft Core: Stainless steel
Wire Length: 250mm
Connector: JST