How does this work? "Rotor BB30 to 24mm Steel Road Bottom Bracket" I'm looking at ways to make a Claris/Tourney crankset fit a BB30 frame. 

I've seen that a "Rotor BB30 to 24mm Steel Road Bottom Bracket" is one of the options to make the two sizes work together. 

When you look at the suggested BB for the Claris, for example, it has the octalink axle for the crank arms to attach to. The Rotor product does not. Is it an adapter that the standard BB goes inside, or does it work differently? 

Thanks.
The Rotor product you've linked to is supposed to be used with integrated 24mm cranksets, mostly Shimano Hollowtech ones, so that option won't suit for mentioned cranksets. As far as I know, tourney requires square taper bottom bracket and you already said that Claris needs an Octalink bb.

You can use a BB30 to BSA interface adapter like SRAM PressFit 30 to BSA Adaptor Kit. With it in place, it's possible to install any suitable english threaded bottom bracket, be it square taper or Octalink. If you don't have a BB yet, you'll have to get one.