In the early 30’s, the patent for the Gillette three hole blade was about to expire. This inspired Gillette, Gaisman, and others to come up with blades that could both be used in the old Old Type razors and also a new razor that would not accept the old Gillette blades. As we know now the Probak won, but for a while it was open for everyone to try. And one of the ones who tried was John Holzman.

And tried he did. To quote the patent:

My invention further contemplates the provision of blades which are designed to fit not only my improved razor, but which are also adapted to t various razors of the well-known Gillette type wherein either a plurality of positioning pins are used, or wherein a blade-positioning bar is used.

Holzman came up with not one, not two, but an impressive twenty one different blade designs that would be accepted by the ‘standard’ three pin razor.

Some of these blades looks too flimsy to be usable, but it looks like Holzman was mostly throwing stuff at the wall and see what stuck.

And what stuck, as mentioned above, was the Probak. Partly for reasons that had nothing to do with shaving, and everything to do with corporate manoeuvring.

You can read the full text of Holzman’s patent over at Google Patents.