Pneumatic cylinder (sometimes known as air cylinders) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion.

 hydraulic cylinders, something forces a piston to move in the desired direction. The piston is a disc cylinder, and the piston rod transfers the force it develops to the object to be moved. Engineers sometimes prefer to use pneumatics because they are quieter, cleaner, and do require large amounts of space for fluid storage.

Because the operating fluid is a gas, leakage a pneumatic cylinder will drip out and contaminate the surroundings, making pneumatics more desirable cleanliness is a requirement. For examples ,pneumatics are used to prevent fluid dripping onto people below the puppets.