The ER-5240M uses 2.25" thermal paper rolls in both the receipt and journal printers. Because this model uses thermal paper an inking device is not required. Both printers can accept the full size rolls of 200' to 230' feet per roll and possibly larger. While you can use the smaller diameter rolls designed for credit card machines you would be changing the paper roll often so just use the big roll it was designed to use. Make sure and leave paper installed on both side even if you don't issue a receipt. You can always turn the receipt off which is better than removing the paper.