Just for the calipers, you just need a regular metric wrench...like Seatman said, 13 mm sounds like it. If you want to remove the braces that hold the calipers to replace the rotors, you'll need a 14mm triple square bit, IIRC. It's either 14mm or 16mm. I had to get mine online because all the stores around me only went up to 12mm. Then I gave up because of the lack of room. I need a lift and I don't have one. If I ever have to replace those rotors, I'll have to have someone else do it.