HUITONG BLOWER DC FANS have the reverse polarity protected.It have various of sizes including 5015,5828,6015,7525,7530,9733,12032,etc.It have the ball bearing and sleeve bearing.It can run on 5V DC,12V DC,24V DC or 48V DC.Special voltage could be customized.In order to meet the worldwide safety requirement.It have obtained the certificates of UL, CUL, TUV, CE, SGS and REACH.