Team Powers made TEAMPOWEHigh venting Cooling Fan, 30x30x10, 18000rpm@8.4V (TP-TTF-PM5301) Cooling Fans engine / ESC / Cooling Fan Specifications:- Dimension: 30mm (L)x 30mm(W) x 10mm(H)- Revolution: 10000rpm @5V, 18000rpm @8.4V- give Voltage: 5V~8.4V- Ball Bearing System- With 18000rpm@8.4V, ~6.5gram of Thrust at 8.4V