FIXIE Colored Brake Cables 
COLOR: FLUO GREEN 
This is just the color of the outer cables. It doesn't mean it has fluorescent qualities.

This set includes the following:

• Front & Rear Outer cable (precut at standard size of 90cm & 160cm respectively) with steel housing and plastic liner.
• 2x Standard Inner Cables with barrel 
• 4x Metallic Brass Nickel Plated Ferulles (Caps for outer cables).
• 2x Metallic Alloy inner cables ending cups.

The included outer cables are made of steel spiral with colored surrounding plastic cover (Fluo Green in this case). 

This helical steel housing is strong enough and appropriate for brakes and you should not use compressionless index-compatible housing instead because the later can easily burst from the braking force and cause a sudden loss of braking function.