What is it?
The SCM regulator is a pressure compensating, low pressure regulator.
How does it differ from other LPR's?
On other LPR's, when you drop or raise the input pressure of your gun, the LPR's pressure setting will change. Pressure fluctuations can result not only from adjusting the pressure settings of inline regulators and/or tank regulators, but also from pressure changes that occur when a gun is fired. The SCM pressure compensates, keeping the LPR pressure consistent in all of these conditions.
How is pressure compensation better?
By compensating for pressure changes, the LPR pressure stays consistent. As a result, components functioning off of the SCM will not experience changes in pressure. That means the components will function with the same forces each and every time. In short, your marker will see less velocity fluctuation over the chronograph.
The AKA SCM Regulator is newer, so it should be commonly available, both new and used.