Bilstein Strut Shock Nut 22mm Socket

Bilstein Shocks/Struts (Maybe other brands as well), require you to hold the shock in place with a allen wrench while you torque the nut attaching the shock to the mount with a socket wrench.

There are custom sockets that allow you to do this but they must be ordered ahead of time and are a bit pricey for a single use tool.

This socket has a passthrough hole for the allen wrench while allowing you to tighten the nut with a box wrench. The torque on these is pretty low, usually 17-20 ft/l