the strut tower? ya know the four bolts in the engine bay that connect the strut plus hold down a tower bar if ya got one.
i think they're 14mm but not sure. i lost one while putting springs on and need to pick up a replacement on the way home.
thanks!

 

There are three per side. Take a wrench with you when you drive to the store. Remove one, take it inside, match it to theirs, buy it, and put them both back on.

NIKE, just do it don't think too much!