Originally Posted by
cehowardGS
Elementary Dr. Watson.
Take the unit to your local Home Depot. They will find the correct screw quickly. And they are cheap too.. 
Oh man, he's on to me.
Well that's what i plan on doing but i noticed that the plastic of the casing is pretty rigid and don't want to use anything larger diameter and/or longer than what Cateye recommends to avoid cracking it.