The Rotur Inside/outside caliper can be used with workpieces up to 7 inches in diameter. The straight end can be used to measure the internal dimensions of narrow projects such as vases and goblets. To get precise dimensions of your workpiece, simply measure the exposed end whilst the other is still in contact with the work.  For repeatable measurements, the calipers’ position can be locked by tightening the adjuster screw. The ends of the calipers won’t scratch the workpiece because they are rounded. SKU: CIO7