Want to learn more about Koleston (numbering system)

[Kathair]

Hi all

I am trying to learn more about the Koleston range.

Why is their a double number at the front instead of just one?

Thanks.

 

[cassies97]

Double base = double coverage. They're meant for resistant whites

 

[Joe96]

Double numbers is double base just like how loreal has 6:0 wella has 66/0