Just checked the one in the garage and it was a 2.5 Tricam that I used. Took the lob on to it too, though I did have the alien. Cant remember what size that was, as it was borrowed.
I've pondered in the past, how close the holes are to the arete, and whether enough force could be transmitted from a cam, during a lob, to bust off the rock between.
Anyone else ever noticed the very small potential placement halfway between the ground and the shot holes. I've never heard anyone else talk about it, but IIRC it looked like it may take a piece (any may actually have been manufactured). Then again, I might have dreamt that, as it was a good while ago.