In reply to Tom F Harding:
Petzl Multihook - although mine is a Charlet Moser one. The plastic cover is not up to the job - mine now has a fold of hose pipe held together with a pop rivet instead. The spanner has been useful on a number of occasions to do up bolt nuts on continental ice - no idea why they should come loose, but the designer clearly thought it was worth putting a spanner on it, and I think he was right.
Good for clearing out blocked screws
Mine's painted red on one side, yellow on the other - helps with aiming the second screw a bit