Labels are bright white for professional results. Labels are smudge-proof as well as water and oil resistant. Fluorescent ink compliant with USPS regulations. These stamps are self-sticking. These labels work with any LabelWriter printer, and are used with DYMO Stamps, Endicia & Stamps.com services. All labels sold by HouseLabels, for use in DYMO/CoStar LabelWriters, are tested to ensure that these labels all fall within DYMO material specifications. Compatible DYMO Printers: DYMO LabelWriter 400 Turbo, Twin Turbo, DUO and DYMO LabelWriter 450 Turbo and 450 Twin Turbo.