Dimensions, the manufacturer of this kit, have their own floss and floss numbering systems. You will have to contact them, since ECS is a retailer, just like any "brick and mortar" shop.
You can contact them at:
www.simplicity.com/contactus
You should have the kit number and kit name aa well as the needed thrwad numbers needed. I am not sure if they will be able to provide it by Christmas.