British ww1 fuze for aviation

[Geertse]

Hello,
Maybe someone knows what this fuze is or has more info about it.
It's not a propeller but on this forum there are many specialists about the subject.
So I try my luck here.
It is marked
H.S.C
3 MkI/L
1917
I've searched the web but found nothing about it.
So all the help is welcome
Thx guys