The Kel McNaughton Caliper is
the only caliper on the market that will accurately
measure both sidewall thickness and bottom thickness
with minimal tangential error, unlike traditional double-ended
calipers. Available in two sizes, the Standard Caliper
will measure bowls or vessels up to225mm (9") deep
and 350mm (14") wide, the Large Caliper will measure
325mm (13") deep and 500mm (20") wide. All
steel construction. is designed for use on hollow forms
such as narrow neck vases, as well as with more open
vessels like bowls.