Three Tools Measure Most Standard World-Wide Threads
Straight gauges in three size ranges and thread styles. All steel. Precision cut threads for accurate measuring. Sizes permanently stamped into each leaf.
Big Book Catalog, Issue:68, Page:479
Big Book Catalog, Issue:68, Page:487
SPECS: English - 28 blades, 4 to 80 tpi;
Metric - 24 blades, 60°; British
(BSW) - 28 blades, 55°.