A brushless DC motor require no point of electrical or mechanical contact between the source voltage and the rotating component of the motor. Because there is no point of electromechanical contact in brushless DC motors they are virtually maintenance free, and motor life is limited only by the life of the rotor bearings. Additionally, because there is very low or no electromagnetic interference (EMI) or radio frequency interference (RFI), brushless DC motors can be utilized in sensitive or explosive environments. With sizes ranging from less than 1" diameter to over 4" diameter and speeds as high as 25,000 rpm, brushless DC motors are a good selection in many high speed, very demanding applications.