Some printers accept any direct thermal label that fits; others only work with their maker's rolls. Neither is automatically wrong, but you should choose knowingly because you'll be buying labels for years.
Who locks in, and how
Printer family
Label policy
What the maker says
DYMO LabelWriter 550, 550 Turbo, 5XL
Authentic DYMO LW labels only
DYMO's user guide: "Use only Authentic DYMO labels"; warranty doesn't cover damage from third-party labels
Third-party direct thermal media within published limits
Width, core and diameter limits in spec sheets
Third-party "DYMO-compatible" and "DK-compatible" rolls exist, but sellers themselves commonly mark DYMO-size rolls as not for the 5XL, and DYMO says third-party label damage isn't covered by warranty.
What you gain with proprietary labels
Feature integration: DYMO's Automatic Label Recognition reports label type and remaining count; Brother's DK cartridges load as a unit, and Brother printers add auto cutters.
Fewer calibration questions: the printer knows the media.
What you give up
Choice and availability: one supplier. DYMO's own 4x6 label page showed out of stock on our check date.
Fewer labels per roll: DYMO 1744907 has 220 labels per roll and Brother DK-1241 has 200, while generic fanfold stacks commonly have 500.
No emergency substitute: you can't use a carrier-supplied or generic roll in a pinch.
We don't compare prices on Packing Desk, but you can check current label prices on Amazon from each label review.
How to decide
You already use DYMO or Brother software across an office → staying in that ecosystem may be simplest.
You ship regularly and want flexibility → choose a generic-label printer such as the Rollo Wireless or Zebra ZD421d.
You want an auto cutter and several label types from one wireless printer → the Brother QL-1110NWB is a reasonable trade.