the only reason I think they are servos is because they are strong and smooth when moving,other than that I have no clue as to what they are,I have not taken them apart.I will take one apart ,and I should be able to tell what they are just by looking at the construction( think) it has been a while since I oppened one up ,maybe technology will fool me.I opened one and the only thing I could see after the first cover was a terminal board with 6 wires all of them the same gauge.no thin wires so I can only think there is no encoder so they must be stepper motors ?.