OK. In a gesture of yuletide generosity I offered to hang a mirror for my neighbour. Its from Habitat, and has holes about 8mm in diameter filled with brown ribbed plastic cylinders with a semi circle cut in the top which looks like you could hang it on hooks. But its a big heavy mirror and picture hooks wouldn't be up to it.
The usual fitting I've seen for this sort of thing is an inverted key hole shaped thingy which you push over a screw head and drop down so the slot holds tight around the head. These are something else entirely. Any ideas what to do with them?