I've only just seen this, think i was on hols when it was posted.
As far as I know there supposed to be about 5 lines on the block, and the main up tolerance up the middle is supposed to be 7b. when i tried it it was about 4 or 5 years ago when i was shitter than I am now (hard to believe I know) and couldn't do any of the main moves, which ain't what i'd have expected on a 7b. I recon its hard for the grade. not been back since.
the left arete is an easier warmup 6 thing too.