Piston based devices can either use air for both strokes, known as Double Acting (DA) Actuators, or air for one stroke and springs for the other, known as Single Acting or Spring Return (SR) Actuators.
Piston Based Actuator
Rack & pinion pneumatic actuator
Compact rack and pinion actuator
CNI, Chemical Nickel Impregnated Actuators
A spring return actuator
Electric actuator,ATEX available