Make one measurement and you have its opposite immediately. These do the work of two standard calipers with far greater accuracy. Simply a pleasure to use. A traditional woodworker's tool modified and improved for the potter.
WARNING: This product can expose you to chemicals including Silica, crystalline (airborne particles of respirable size), which are known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov.