1-1/8" × 3-1/2" format. Direct thermal printing. White self-adhesive labels on rolls. For use with LabelWriter 5XL, 550, 550 Turbo, 4XL, 450, Wireless, 450 Duo, 450 Turbo, 450 Twin Turbo and Desktop Mailing Solution printers. Pack of 12 rolls with 350 labels per roll, for a total of 4,200 labels.