2.3 x 10 Internet Postage w/Delivery Confirmation Labels Dymo 30387 Compatible for DYMO LabelWriters 330 400 450 Twin Turbo Duo 4XL Printer Compatible with DYMO 30387 Internet Postage w/Delivery Confirmation Labels / Dimensions 2.3" x 10" 1 Roll / 100 labels per roll / 1 inch core High quality, bright white direct thermal paper Strong Adhesive/ Water Resistant / Color: White