Agroshield
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They go in a pipe threader.
They are similar to the dies that go into a pipe threader, but the ones he shows do not go into a pipe threader. First, because none of them are pipe threads (9/16 - 16 is standard BSF and left hand to boot) and second because Mr Alfred Herbert, of the AH initial inscribed upon them, was rather more well known for his Coventry die heads.
There is a book, called 'The book of the Coventry die head' that will help you identify which particular die head they will fit.