The main components of a cylinder include the cylinder body, head end head, crank end head, piston rod, piston, packing, suction and discharge valves, valve retainers and valve caps. Cylinders can be double acting or two single acting cylinders can be combined to create a tandem cylinder. An example of a double acting cylinder is an 11K and an example of a tandem cylinder is a 9-5/8K-CE x 5-3/8K-HE-FS.