Alternative parts for rare soft axles - Sheepo's Garage
Lego pneumatics - Wikipedia
Lego compatible pneumatic tube
MOC Technical Parts 1meters Technical Pneumatic tube Internal DIA 2mm External DIA 4mm compatible with lego for Kids Boys Toy|Model Building Kits| - AliExpress
Price history & Review on MOC Technic Parts 1 meters Technic Pneumatic tube Internal DIA 2mm External DIA 4mm compatible with lego for kids boys toy | AliExpress Seller - MOC2017 Store | Alitools.io