a whole set and you have to do trial and error to find the best fit, not too tight, not too loose. oh joy.
Google or check this forum for a shimming guide.
FOUR DOLLARS Canadian or 212,005,394,295 Zimbabwe Dollars
24 pc set
6X 0.1mm
6X 0.15mm
6X 0.3mm
6X 0.5mm
http://www.airsoftparts.ca/store2/in...roducts_id=880
one tip, when I took mine apart, I noted which shims when on which gears so I kind of had a head start of what thicknesses to start with.
On my second JG g36c mechbox I just got a Modify gearset and popped it in the mechbox. It is pre-shimmed.