If you are a seller on Amazon, Avery 5160 for laser printers (1" x 2 5/8") is a very popular size for FBA labels. We also sell other FBA approved sizes in blank labels here: https://www.avery.com/blank/usage/amazon-fba-labels
Checkout our Help article on FNSKU barcodes here:
https://www.avery.com/blog/fnsku-vs-upc-what-barcodes-do-you-need-for-amazon/
Here is our article on printing Avery Shipping Labels as an Amazon Seller.