The Fowler 52-485-048-0 Thread Wire Measuring Set covers threads from 3-48 threads per inch. The laminated conversion chart provides the information to measure threads accurately. 16 sets of 3 wires covers a wide range of inch as well as metric thread sizes. All packed in a handy storage case. Fowler, an American company, manufactures inspection and measurement instruments such as electronic indicators, calipers, bore gages and digital scales. The company founded in 1946, is headquartered in Newton, MA.