From my limited range of understanding, I gather that the very first design of the 24, (like the one in Guidos' photo) were made from modified 2-5 blades. As such, they would be 3/16" stock blades. The guardian first appeared as a standard offering in the 1979 catalog, and until at least the printing of the 2006 catalog, it is described as being made from 1/8" stock. I've seen both 1/8th and 3/16, and I'd like to get a better feel for when the change actually came about. If you have a guardian, or bunches of them, please check them, if you know when it was made, or if the handle shape is fishtail, rounded, etc... please post up, so we can figure out when the switch from 1/8th to 3/16 occurred. Many thanks!