Pneumatics Kit 2A - Double Acting Cylinder Add-On

Pneumatic cylinders use compressed air (rather than motors) to produce motion that rests in one of 2 states: fully extended or fully retracted.

The cylinder in Pneumatics Kit 1 is single-acting -- it uses air to extend the cylinder rod, but uses a spring to return to its contracted state. As a result, the cylinder may expand and contract at different speeds.

In contrast, the cylinders in Pneumatics Kit 2 are double-acting and use compressed air to both extend and retract.