MOC Technical Parts 1 meters Pneumatic Tube Internal DIA 2mm External DIA 4mm Compatible with Lego for Kids Boys Toy 5102 21670|Blocks| - AliExpress
LEGO® 99021 6167942 - 6265670
Lego compatible pneumatic tube
Pneumatic Wheel
Lego compatible pneumatic tube
Quickun Pneumatic Tubing 6mm x 4mm PU Polyurethane Tube Air Hose Line for Air Compressor Fitting or Fluid Transfer ( Black 32.8ft/10Meters ) - - Amazon.com
1/4 in. OD Polyurethane Pneumatic Tubing - AndyMark, Inc