"Dave Liquorice" wrote in message
ll.net...


True enough but you've looked at your screw and it has the X on the cross.
You have two screw drivers without PZ/PH markings. How do you know which
is the pozi one *without* checking the fit?

You look at the sides.. the pozi has parallel faces and the philips has
tapered faces.
Its the parallel faces that makes pozi less likely to pop out.
The extra corner nicks in the screw head are to clear the bits left by the
grinder on the screwdriver blade, although with modern manufacturing methods
you don't always get those leftovers on the blades these days.