Also...make sure you get hardened bolts.. not soft, cheap, generic junk.
I'm assuming you're riding something relatively normal, but on my DH bike, I did have all 6 front rotor bolts simply shear off, when I'd had to clamp down on the front, in the middle of a rock garden. Yes, I was running a 225mm front rotor, and 6 piston hydraulics..so it wasn't exactly everyday brakes, but it DOES happen. --was a massive brown-trouser moment BTW..
See if you can ideally get them from the manufacturer, .. you can get hope..etc bolts on
Ebay, but don't just use generic hardware store junk.. for your own sake...
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Cycle related blog entries, including a few 5 minute reviews:
http://anotherdooratthe.endoftheinternet.org/category/cycling/