Of less utility than you might think because for example the Mustad 98480 is not the same as the Tiemco 100 at all in terms of size nor proportions (even though most charts will list them as equivalents) only in terms of use (i.e. both mainstream dry fly hooks). Might have some use for beginners, but for the most part you are better off knowing you need a 1XF hook than a series of random manufacturer model numbers. YMMV.