Lid Master Calipers 20"
Giffin Large Lid Master Caliper: Accommodates larger pots up to 20 inches.
Make one measurement and you have it's 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 reassemble the wing nut and screw in the 12-1/2% hole. This way your lid will shrink to fit the pot.
A traditional wood worker's tool modified and improved for the potter to make lids for any pot. Take one measurement and you have its opposite immediately. Does the work of two standard calipers with far greater speed and accuracy. Standard Lid Master sizes lids up to 11 1/2", Large Lid Master sizes lids up to 16 1/2".