yeah, loco is right. the only time youll see 5mm is in a longrod motor. this is when the crankshaft has 5mm longer connecting rods on it. it doesnt give much of a powergain, but it does decrease wear on your pistons. in this case to allow for the extra length you run a special series piston. the wiseco 795 is what you need to run, if this is the crank you own, or just want to own.