Front Brembo bleeder screw size/PN?

Having daily driven my '09 V for 7 years through Buffalo winters I'd be willing to bet a bleeder screw or 2 is going to snap when I try and bleed my brakes this weekend. I went to change the pads last week and the inner 2 caliper pistons wouldn't press back in their bores so its time for a rebuild and bleed. Maybe its bad karma but I'm trying to have a couple bleeder screws on hand in case the inevitable happens. I bled them 4 years ago and it was a struggle with heat, penetrating oil and working them back and forth. I think I gave up on 1 screw cause I was afraid of breaking it.

I've searched the forum and google and cant seems to find a definite answer on bleeder thread size and length. Also, in the aftermarket there seems to be zinc plated steel and also stainless available. What's OE material? Thanks in advance.