This aluminum hard line equals the following equivalent 1:1 size at each scale.
1/25 scale = 2"
1/16 scale = 1 1/4"
1/12 scale = 1"
1/8 scale  = 5/8"

Depending on your scale, typical uses are larger coolant (radiator) and fuel lines, like from the fuel cell to the fuel pump on a FC or TF dragster, as well as other larger fuel lines. At 1/16 scale, it could also be used for headers and exhaust pipes.  Drill the end out to simulate a hollow pipe. 

This solid core aluminum is easy to bend and shape to your installation and is already highly polished looking. 

See Pro Tech Fittings sized at .080 for this hard line.

We're about half of the price you'll find elsewhere.
Each package contains one coil of .078 x 12"