S-T Industries catalogue comprehensively covers the range of hand gauges and tools used in general the engineering and allied industries. The small bore diameter gauge shown below may be supplied to measure bores down to 100/150mm  in dia. ranges.: 10 to 18 /18  to 35/35 to 60/50 to 100/ 50 to150mm with imperial equivalents.

Shown here is a small bore comparator which, using a range of small add-on anvil tips measures between 10 and 18mm diameters. measures bores