This .045 diameter braided line equals a 1:1 size of:
1/25 scale - 1" or -16 AN used for larger fuel or oil lines, larger water transfer lines
1/16 scale - 1/2" or 5/8" or -8, -10 AN - typically used for fuel, coolant and oil plumbing.
1/12 scale - 1/4" or 3/8" or -4 or -6 AN - typically used for brake line applications, small oil lines, some small fuel line applications like nitrous, pressure gauges and vacuum lines.
1/8 scale - Less than 3/16"
The scale size is determined by its outside diameter (OD) compared to real world braided line since an inside diameter isn't useful in scale modeling. See the tables in the section called LINKS, INFO & TECH.
Use Pro Tech Fittings for .045".
Each package contains one coil of .045 x 18", by Pro Tech.