To do with wire used would be my guess. Kanthal A1 l to hit .2 you would need 22Gauge that is way to thick in a stock coil head. Rubber grommet will not sit flat. SS316L is a lot lower resistance and a higher gauge wire (thinner) can be used. For .5 I can use I believe 26 gauge Kanthal A1 to hit that mark. This is only a guess on my part but I don't see any other way. CHEERS!