STI thread gauges for UN-8, Unified constant-pitch thread

Eight threads per inch across all diameters — the series for large threads where a proportional pitch would come out too coarse. STI gauges check the oversized thread that later receives a thread insert. It is a series of its own, because the receiving thread is larger than the working thread that follows.

VÖLKEL offers 28 versions, from UN 1.1/8 x 8 to UN 2" x 8.