Nut runners are controlled nut drivers that include torque transducers. Both electric and pneumatic devices are commonly available. Pneumatic nut runners are powered by compressed air and vary in terms of air fittings and air consumption. Electric nut runners use a DC controller as a power supply. Hand held cylindrical devices are lightweight and portable. Pistol-style devices with trigger actuators are also available. Large nut runner systems are designed to be mounted in a fixed position, usually on an assembly line. Fixed square drives are designed to accept sockets with standard sizes of 1/4”, 3/8”, 1/2”, 5/8”, 3/4”, and 1”. Adjustable size drives and metric devices are also available. For nut runners with adjustable heads, suppliers often specify an adjustable range.