4011 and w100 are the same thing 4012 and W500 are the same then you have the newest reducer which is for automotive only the way I understand it.I order Wicked reducer, but they sent me Auto Air reducer 4011. I assumed that meant they were compatible. I misread what someone above wrote. They said 3 to 1 reducer to paint. I misread as 3 to 1 paint to reducer. I guess that could explain some things. hehe
But with Wicked I think that the 4011 does work a bit better then the 4012 .
On I think all the bottles of Wicked it says 3 to 1 reduction , That is a starting point on black or white through a .35 I usually start at 5 to 1 @ 25 to 30 PS. The lower the pressure the more reduction is needed.