The Screw Tapp 4x16 is the cheapest item from this partsfiche.
A sample from the products for the Winker include: Screw Tapp 4x16, Socket,bulb (2p), Bulb 12v21w, Sub Assy.,r,fr.wi.
The five St1100p Paneuropean 1996 (t) Spain Australia / Kph Winker component parts are all listed in this schematic.