Wallpaper is printed in batches. It is important to have the same batch number, to ensure colours match exactly. The batch number is usually located on the wallpaper label close to the pattern number. Different batches can result in minor differences in terms of pattern, colour, sheen, and structure. The differences might not be immediately apparent but once on the wall can be quite obvious. Be sure to buy enough rolls for your project; don't forget the reserve roll!