Abstract: Key assemblies to mechanically key pluggable-module sockets are described. A disclosed example key assembly includes a key having a shaft, a first radial protrusion extending from the shaft and an annular guide surface on the shaft; and a key base having a plurality of fingers defining a plurality of radial slots and an opening to receive at least a portion of the shaft, wherein at least one of the fingers is to engage the annular guide surface to enable the key to rotate to a set position, and wherein the first radial protrusion is to engage one of the slots to rotationally hold the key in a set position when the at least one of the fingers forced out of engagement with the annular guide surface.