The 'handing' can be seen at either end of the only straight edge of each pad. In the picture above the 'A' end shows the curve coming down the side of the pad to meet the straight edge
but before it does so it takes jink out from the curve
then a sharp turn back in to meet the straight edge
which results in a sticking out 'lump' (detail below). On the 'B' end the curve follows smoothly round till it meets the straight edge. There is a cut-out in one part of each half of the caliper (can't recall if it is at the top or the bottom) to accept the 'lump' at the 'A' end of the pad
which is why they only fit one way.
