Hi joe…We will be climbing trad, not on bolted rock. I roso it doesn’t use numeric grades, but to be honest if you’re seconding 4s and haven’t started leading yet or been on outside rock it doesn’t sound like the ideal session for you….it’s very different to seconding bolted routes indoors and to be honest Ouse probably be better getting somebody who’s a qualified instructor like Andy to do a few introductory sessions with you first. You’ll love it once you get into it, but there is quite a lot to take on board.