The initial concept of the backpack company was to make the design very simple and noticeable. We always have a charcoal grey outside that is PVC coated to make it water resistant. The inside colours depend on which series you become a part of. The Day 1 logo is green, orange, and yellow. The inside of the backpacks match those colours. So, our initial run of backpacks have a solid green, orange, or yellow on the inside.