What kind of insulating castable?

Newbie here! Our local refractory has FOUR different options for insulating castable and I don’t know what to choose. Advice? https://ssfbs.com/insulatingCastables.php

Seems like they’re mainly different in their max temperature ratings. Depends on the price difference I would think. 2600 should be enough. I don’t think you need 3000 but again, If it’s a few dollars then why not.