Doesn't matter to me the steel. I use the 50 grit mustard yellow 3M belts on all of em! I get incredible life out of these belts too. Even the 80 grits seem to last longer than the blaze orange ones I have which are good but they don't keep up with the yellow ones in my experience. I use some Norton aluminum oxide belts and also the Trizact belts which are others I get some incredible life out of.
These seem to do all I need. The aluminum oxide belts are kept here between 100 and 320 grit. After that I use Trizact. I do go through a lot of the aluminum oxide belts but being that I'm sanding a lot of wood and micarta, g10 and other things such as this I just feel using ceramic belts on these gums up belts needlessly so I kind of use the aluminum for all but metal. I still have some of the old blue zircon belts but have rarely pulled them down since finding those 3M mustard yeller ones Reese Weiland turned me on to some time back.
STR