The SAM4s ER-5115 uses 44mm bond paper rolls and the ERC-18 ink ribbon cartridge. Please note that there is also a model with a very similar model number that uses a different ink ribbon. This page is for the ER-5115 not the model ER-5115-II that -II makes a big difference in the ribbon. Please confirm if you are unsure before you order.
Make sure you keep paper and ink in your register, failure to do so could result in damage to the print head or other parts of the printer.