I bought the OS Four Stroke Valve Adjustment kit from Tower.
http://www2.towerhobbies.com/cgi-bin...?&I=LXCN31&P=0
The thin gauge is .0015" and the thick one is .0040"
What I've heard recommended is a "Go" / "No Go" approach when doing the adjustment.
If the thin gauge will go betwen the valve and rocker arm, and the thick one will not, your adjustment is good.