DFROBOT DSS-P05 Standard Servo (5kg) DSS-P05 Standard Servo high torque servo, suitable for the production head, arm, biped robot, etc. This is a special servo without hardware stop, it depends its internal potentiometer to detect the angle. So the power will be a very important parameter. Please make sure that you have enough power like 5~6V. Or it will keep rotating, because it doesn't know where it is.