Are ink cartridges required?
No. Printing is thermal transfer, with no ink or toner.
How do I choose the right diameter?
Based on the cable diameter (including insulation): the tube must cover the cable before shrinking and grip firmly afterward.
What is the difference from DYMO tubes?
These are compatible with Brother P-Touch and AIMO printers (HSe system), whereas the DYMO Rhino ID1 tubes are for DYMO machines.