This clearly isn't classic and vintage, but you guys seem to have more knowledge about such things, so here's my question. I am looking for a Record 10 speed 11-23 cassette. And I am seeing new Record Ultra Drive cassettes all of which have the last four cogs being titanium on a carrier. But I see some where all the other cogs are completely metal without any drilled holes and I am seeing others where cogs 3 thru 6 have drilled holes. Both configurations claim to be Ultra Drive cassettes and both are Record. Are there two versions of these cassettes, one with solid metal throughout and one with the drilled holes in the middle range of cogs? Are the ones that are solid metal throughout all titanium cogs and the other version is nickel/steel or some other metal in the middle cogs? Please enlighten me. Thanks!