6a, A1+. See Vallot guide for a reasonably detailed description. Some tips for the S to N traverse: (1) The route up the Crocodile is not well described. Go a little up the icy chimney until possible to move leftwards along a line of weakness. This leads to a niche, from where a short, awkward chimney is followed to the arete. Easy ground from there to the summit. (2) All ab points had in situ pegs and tat of at least ok quality in July 2010. (4) Penultimate ab off the Caiman (to get down to the snowy ledge on the Chamonix side) is over 30m. Might just get to an intermediary ab point on a 70m rope with rope stretch. It's a blank wall, so downclimbing is not an option. Therefore one 60m rope won't be sufficient!(3) Final ab to the Col du Caiman just about doable on 60m ropes with rope stretch but beware jamming the ropes in the crack running down the ab line. To help avoid jamming, consider doing two abs using an intermediary ab point - however the second ab will then be in excess of 30m even with rope stretch, leaving a tricky down climb (possible to set up a second ab point - this is not in situ). A 70m rope would be helpful. (4) One 60m rope sufficient for all other abs and also for all pitches (can double up the rope if need be - the harder pitches don't exceed 20m). Consider taking one 60m rope and pull cord for a retrievable abseil to deal with the couple of long abs. (5) A1 slab on the Fou has three in situ pegs (July 2010), which can be supplemented with some micro wires but not essential. (6) Vallot refers to a down climb onto a rounded arete to get off the Fou. Not clear what this refers to. Instead, scramble down the path of least resistance on the Envers side to reach an ab point (hidden away on the left looking out, possible ab from a little higher up to get to it) and do two abs to get to the system of rising ledges and weaknesses that leads round the Ciseaux. (7) There are several ab stations on the Bregeault Ridge (the main ridge under the N Summit of the Blaitiere - to get there, cross a narrow subsidiary snow couloir to the left (looking out) of the Spencer couloir). (8) Recommend full set of nuts and cams (BD 0.3 to 2, 3 not essential).