Not considering brass, stainless steel and bare metal finishes, it seems that there are more finishes for aluminum than Type II and HAIII. MTE and Romisen have some other finish, and perhaps it is a variant of Type II. Today I noted KD has a new pair of EastwardYJ lights with a finish called HRC 20-30. I did some preliminary research and discovered that this is a hard finish often used on gears. Anybody know more about it and if it is harder than HAIII?