Air cylinders are mechanical parts that produce linear motion from compressed air. Air cylinders are usually considered to have a simpler mechanism and provide smoother drive than oil-based hydraulic cylinders. They are composed of a cylinder and piston, and prevent compressed air leaks using seals made of rubber or other materials. Air cylinders can be differentiated by the different ways they operate in combination with the motion of their spring. Examples of these different operation types include single-acting (push type), single-acting (pull type) and double-acting. Push-type single-acting cylinders have a valve that is normally kept open by the spring force and closes only when the cylinder is pressurized. Pull-type single-acting cylinders have a valve that is normally kept closed by the spring force and opens only when the cylinder is pressurized. Double-acting cylinders don't use the force of a spring. Instead, the pressure is divided between a top chamber and bottom chamber to open and close the valve. Different cylinders should be used for different operating environments since there are cylinders designed for use with specific conditions such as high speeds, high frequencies, ultra-low speeds, heat resistance, cleanrooms and vacuum. MISUMI handles several well-known brands such as SMC, CKD and Koganei.