LEGO Black 4mm Diameter Pneumatic Hose 19.2 cm (24 Studs) (63540) | Brick Owl - LEGO Marketplace
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
Sheepo's Garage: Alternative parts for rare soft axles
Hose, Pneumatic 4mm D. 54L / 43.2cm : Part 5102c54 | BrickLink