Currently we support the following label sizes for the Dymo printer; 30252, 30334, and 30336. We have attached a label reference guide for you as a seller to help you pick the right label for your workflow and product niche.
For example, the 30336 is the perfect label size if you send in a lot of books or smaller items. Larger labels might wrap around the corners of some products as you try to label them. Most sellers use the 30252 and the 30334 however.
One place to purchase labels besides Amazon is: https://www.onlinelabels.com/
Dymo Label Reference Guide
But this varies along with the model as well.
Ex: Dymo 450 works best with 30334 labels.