Media and use
Tape compatibility and surface fit
Label tape is not a generic width of plastic. A cassette has a physical format, a printed face, an adhesive and a set of manufacturer instructions. The machine's supported media is part of the model identity.
Width is necessary, not sufficient
The Brother PT-N10, PT-N20 and PT-N25BT are listed for Brother Btag cassettes up to 12 mm (about 1/2 inch). The Btag family page names those three machines. That does not mean another manufacturer's 12 mm cartridge—or another Brother tape family at the same width—will fit. Check the cassette series, not just the tape width, and retain the model suffix when matching the machine to an offer.
Buying bundles also need a close read. PTN10231BUND and PTN20231BUND include a black-on-white Btag231 4 m cassette; the base model pages list a blue-on-white sample. PT-N25BT package variants add different colors or amounts of tape. Those extras can make a starter pack more convenient, but don't change the printer's operating system or make it accept another cassette family.
Some machines take paper-label cassettes too
Not every label cassette feeds a continuous strip. The discontinued Brother PT-2610 guide documents Brother/Avery AV die-cut paper labels for address, return-address and file-folder sizes, printed one at a time; the same machine also accepts separate TZ tape. Check the exact model and AV stock code because these fixed-size paper labels are not a generic cassette or a roll. The PT-2610 review explains the package, desktop software and limits of this legacy route.
Read the PT-2610 assessment before treating an old machine or AV refill as a current-ready purchase.
Surface behavior is a separate question
A cassette that fits is not automatically suitable for every surface or environment. Brother's official Btag material describes water, temperature, fade, microwave and dishwasher resistance within the range stated for the tape family. That language should not be read as approval for every material, temperature, cleaning routine or direct-contact use. Follow the package and tape instructions for the precise cassette you plan to use.
The PT-N series user's manual cautions that labels can peel or become permanently fixed, and that color may change or transfer depending on the area, material and conditions. It notes that wet, dirty or uneven surfaces can be hard to label. The manual recommends testing a small piece on an inconspicuous area. That is especially sensible before labeling a reusable container or a surface that could be damaged by residue.
Plan the shape and text together
The three models in this family share half-inch tape but differ in maximum combined print height: Brother lists 7 mm for the PT-N10 and 9 mm for the PT-N20 and PT-N25BT. The N10's smaller screen previews text and length; the two larger-body models preview an image of the label. A short name may not need the bigger preview. A two-line label with more detail may benefit from the taller print ceiling, though it still has to fit on the tape.
For contrast and readability, inspect the color of the lettering as well as the label background. A light print on a pale surface can lose contrast, and a clear label can expose the surface color underneath. Use a test print to confirm that the real label reads well on the real item before making a batch.
Compare the PT-N10 assessment, the PT-N20 assessment and the PT-N25BT assessment for their package variants and limits. Then review the exact cassette's care directions; the small machine is only one part of the result.