Just want to say, they actually work! everyone should have one of these in your tool box.
I was on the last stage of putting my Engine back in, tightening the nuts on the studs on the bottom of the Engine and one broke, this is after installing the Engine putting the cage back on, hooking up the starter and electrics and cooling hoses.
the Speed out tool has 4 sizes, I figured I'd start with the smallest, the larges size is the one for a 10 mm, first size, no luck, second size, the busted stud came right out.
good investment that saved me many hours and frustration, I've uses easy outs before, this works better, at least this time

You own stock
Good to know,probably get a set