No Longer available from BMW, but Halfords universals are a pretty good substitute for £9.99:
with a bit of modification by cutting the lower section off:
and attaching the 4 fixing clips:
They now look like this:
They mould pretty well to the shape of the car, cover the soon to be repaired rusty front sill edge, and generate a saving of £25 over the original BMW type, (that's if you can find any...)