[masraum]

Originally Posted by cabmandone

The only difference is how they attach to the tool. Mine takes the second one that is held on with flange nut that is supposed to be tightened with a spanner tool.

I shouldn't say "only". I think the one with the thread on interface costs more too.

The other side of the one that is threaded looks like the one that isn't threaded. I think it would require the jam nut in addition to the threading on the disc itself. The price difference was 20¢. It seems like they should both be able to be used on the same grinder, just one without the inner nut/flange and the other with both nuts/flanges.