Abstract: A positive displacement, progressing cavity device with interengaging axially twisted rotors that define sealed cavities or chambers which develop at the inlet of the device and progress axially to the outlet of the device in response to synchronized rotor rotation.As the cavities or chambers progress axially they may be constant in volume, increasing in volume, decreasing in volume or any combination of constant, increasing and decreasing volume depending on the change in pitch of the axial twist of the rotors. All rotors of any one device are identical in geometric configuration and are arranged in groups of four, such that each rotor is in constant engagement with its adjacent rotors.