Amazon.com: TEESE 21pcs Pneumatic-Kits Compatible with Lego-Technic-Parts, Piston-Pressure-Rod, Air-Pump-Cylinder-Hose, MOC Car Truck Replacement Parts : Toys & Games
LEGO Technic Universal Pneumatic Set #8044 Vintage 1980's | eBay
Building A Hydraulic Lego Excavator Using Standard Pneumatic Cylinders | Hackaday