We use this label in our shop.
It fits our two printers  a Zebra GK420TM  desktop printer and a ZEBRA P4T mobile printer, so should fit other printers as well but please check.

These sticky labels are yellow paper they are perforated between each label so they can be torn of with the backing paper still on  which we have found usefully because they can be slipped behind clear shelf edge strips and taken out just as easily. They can also be easily peeled of the backing strip and stuck directly on the product or stuck any where. The labels are on a 19mm cardboard core, there are 500 labels on each roll the diameter of the roll is 55.4mm . on the rear  of the backing paper there is a black printed line between each label it seems our mobile printer needs this to correctly aline the label.

This yellow label as been very effective as a price reduction label  (similar to ASDA's OOPS label)

Our MD had to buy shed loads of rolls of this particular size as he could not find an off the shelf size in yellow to fit our printers so we thought it a good idea to put on our web page to see if any body else was needing them. 
The price is for one roll  of 500 labels if you need more rolls please ring 01282 868204 and speak to sales and we should be able to do a better price. The carriage charge should be less than our standard price also.