From the Knit Rowan website -
Don’t miss out on some exclusive new colours from Kaffe Fassett for our Handknit Cotton range. Selected specifically by the man himself, fifteen bright and colourful shades make up the new, limited edition palette.“

Note - these colors are not currently duplicated in the Rowan Handknit Cotton range. The color numbers are unique to this collection, which is why this collection is on a separate page.

This way, Ravelry members can post and search stashes for these colors and not be confused with the core colors of the yarn.