This black soft line has a .050" (1.3mm) diameter.  See the sizing table below to determine the real world size at your scale. 

This is real rubber and it will bend and drape easily without kinking. 

Depending on your scale, typical uses are medium to large coolant, heater, radiator and A/C hoses. Can also be used for larger electrical wire.

Equivalent 1:1 sizes at each scale:

1/25 scale = 1-1/4"
1/16 scale = 7/8"
1/12 scale = 5/8"