Make lids and throw pots at the perfect size with these plastic Giffin Grip Lid Master Calipers that help account for shrinkage! When used to measure a pot opening at one end of the calipers, the clever two-way design automatically gives you the measurement for the lid at the other end. They also feature two holes where the wing nut can be attached—use the upper hole to take precise measurements, then move the wing nut to the lower hole to adjust for shrinkage. The lower hole takes the typical 12.5% shrinkage of most plastic throwing clays into account so you can size your work accurately without needing a separate shrink ruler. - Giffin Grip Lid Master Caliper - Standard, RedLid Master Caliper, STANDARD -