slam bag bolts

what size and length bolts do i need to get for my front slams? i think there suppose to be grade 5 or higher

GRADE 8 BOLTS always grade 8

and they are 3/8 if I am correct, and the length depends on the thickness of the bracket and the thickness of the washers used.

alright thanks man

gravity5 is correct, and just another note, 1/2in length bolts are almost always too small.
Mike