How thick are your sheet labels?
Our custom sheet labels are 8.31 mils +/- 10% (0.00831 inches or 211 microns) thick. Keep in mind, mil is not short for millimeter. Mil is a commonly used measurement for products like labels and stickers. It's equivalent to 1/1000 of an inch. You can read more about using mil as a form of measurement on Wikipedia.
Without the paper backing, the sheet labels are approximately 2.6 mils thick including adhesive.
Label: 2.6 mil (.0026 inches +/- 10%) Backing: 4.1 mil (.0041 inches +/- 10%) Laminate: .81 mil Total: approx 8.31 mil (+ or - 10%)