What is the difference between PromoCell Medium "ready-to-use" and PromoCell Medium "Kit"?

PromoCell Cell Culture Media "ready-to-use" consist of basal medium and SupplementMix. PromoCell Culture Media Kits consist of basal medium and SupplementPack. Addition of the supplements (SupplementMix or SupplementPack, respectively) to the appropriate basal medium will result in identical growth media.