This a soft rubber tubing that is easily configured to the space you have. It's able to bend at a sharp angle without kinking.
See Hex Fittings sized at .060 for this soft line.
This soft line equals the following equivalent 1:1 size at each scale.
1/25 scale = 1 1/2"
1/16 scale = 1"
1/12 scale = 3/4"
1/8 scale = 1/2"
Depending on your scale, typical uses are smaller coolant hoses and larger fuel lines, as well as other transfer lines. The current trend in TF is the use of black lines instead of braided lines for fuel, from the pump to the barrel valve and for the injector lines at the 'hat' and the manifold.
This soft rubber line is easy to bend and shape to your installation.
Each package contains one coil of .059 x 18"' rubber tubing