Bolt size.
 

I recently had my first issue with my Rx8. The bolt holding the e-brake bracket onto the caliper came lose, and caused my e-brake to stop working. If this happens to anyone else, the bolt size is 10 x 1.25 x 20. Skip going to the auto parts places, go straight to Lowe's. It took me forever to try to find this bolt, and when I did, it was at Lowe's. Make sure to get the lock washer as well.