This is an MX compatible switch, the Gateron Oil King switch.
It is a linear type with lubed switches, providing a very smooth keystroke feel.
Linear
Stem: Black POM
Actuation: 55±5gf
Bottom Force: 65±5gf
Spring: 20mm
Total Travel: 4.0mm
Top Housing: Black Nylon PA66
Bottom Housing: Black INK Housing Material
PCB Mount, 5-Pin
MX Style
Factory Lubed