Idle Jet IDF only
Jets are sized in "milimeters", so a "50" jet is very close to .5mm. Actually they are rated on flow not size, after they are measured on a flow machine. That's why drilling and reaming jets is not necessarily a good idea, since drilling or reaming can result in a 55 idle flowing more than a 60 idle, based on orifice length and entry/exit radius, etc.