A Skid mount is a popular method of distributing[1] and storing machinery[2] and usually-stationary equipment for the military and industry on its own or with other units as part of a modular system (modular process skid).
The machinery at point of manufacture is permanently mounted in a frame or onto rails or a metal Pallet.
They often have standard sized holes (called "pockets") for a forklift truck to slide into it to lift it safely.
As well as making it more transportable, it adds stability when static.
[3] To facilitate factory floor efficiency, machinery such as laser welders, plastic injection molding units, lathes and sewing machines are often skid mounted for easy placement according to work flow needs.