Compresser...when i had my neumas my monthly bill doubled....and if your fancy compresser dies you will have one heavy repair bill that may require 3 days or more before its returned...man i can get a new electric supply the next day for $50 or more....its a road that maybe aint worth travelling ha ha...electric is cleaner more efficient and dont cost the earth...ask yourself this...why did neuma make a electric module when air power was supposedly the way forward?....Nuff said.