A while back a friend traded me a Solothurn 20mm HE round that had this fusing on it. After a bit of digging around, I discovered it was a AA round used by the ground-based 20mm AA gun. The fuse nose is recessed slightly to house an aluminum hammer.
It is marked ASB for the manufacturer Deutsche Waffen und Munitionsfabriken (DWM) in Werk Berlin-Borsigwalde. It is dated 1943. The fuse is marked 20MM Kpf.Z.46

