This is the smallest black soft line I have.
This is a shiny black nylon line.
It is slightly springy and can be bent at sharp angles
The OD dimension is .0047" or .14mm.
Typical uses are small oil lines, vacuum and fuel lines, especially fuel & nitrous delivery at the the carbs, blower manifold, injector plate or injectors.
Each package contains one coil of .005" x 18" soft line