I have the small screwdriver kit you make. (Forgot the name) There are J1 and PH1 drivers. However, apart from the stamped label, those two especially are identical. The J1 is as rounded as the PH1 and all angles and lengths are the same. (I looked closely with a good magnifying glass.)

There is a very visible difference between J0 and PH0. So I assume either my PH1 or my J1 has a manufacturing error.