I'm looking to getting something like those, 8mm sounds good enough.except they still hold on to plenty of thread to be more than safe. If they were more than 8mm you would be pushing it as far as safety goes but 8mm or less and you still have a good 1/2" to hold on to.
With 8mm simple spacers you aren't going to hurt anything, its going to cost you less than 35$ and it is going to look better. If that is what you are looking for, spending more is just spending more money. period..
FYI, I have been running for 18000 miles now with 8mm spacers I haven't had a single lug nut come loose or a single vibration issue with a <35$ set of spacers from ricer zone..
Any specific brand from autorice? Any specific type of metal they should be made of?