Hobbywing made FAN-3010BH-6V-11000RPM@6V-0.19A-BLACK-A 30860103 (HW-30860103) Cooling Fans Motor / ESC / Cooling Fan
Using this fan mounted onto your ESC heatsink, then you'll definitely have the maximum cooling performance.
Specifications: Ball Bearing/Non-waterproof/JR-3P Male Plug/L=50mm
Applications: XERUN XR8 Plus, XERUN XR8 SCT, XERUN SCT Pro