The 22m inserts are meant to fit into the Open Top style Thermal P Nail. The “PB” is blasted on the outside walls to represent Pukinbeagle. These inserts have an 18mm inner diameter with 2mm walls resulting in a 22mm outer diameter.
The inserts with a 20mm or smaller outer diameter come without the “PB” insignia blasted on them. The 20mm inserts are made for the Low-Profile Skillet by Pukinbeagle. The 19mm inserts are designed for the Deep Dish Dnail by Pukinbeagle. Contact me if you need help!