Yes, they were a true A shape, when they were put in I questioned their suitability. Took a long time to move, but when they did it made a right mess.They are very heavy ,(3.5m = 3.25t ) , their shape means that the weight of the grain against them presses down on the sloping base and adds to the weight and resistance further.
The trouble with some designs is they are a true "A" shape and the grain is solely pushing them away , not trapping them so to speak.
We have sold thousands and never heard of them slipping, except of course when machines push to hard against them.