Make one measurement and you have its opposite immediately! It's an easy- to- use, accurate way to size lids for pots. You can also make a lid for an already fired pot, by reassembling the wing nut and screw in the 12-1/2% hole. This way your lid will shrink to fit the pot.
This product functions in the same way as a regular Lid Master but allows you to work with larger pots up to 20 inches or 50.8cm in diameter.