It's a hot gas bypass/desuperheating control, not a metering device like an expansion valve. It's made up of a HGBP valve, a temperature piloted expansion valve for desuperheating and a mixing chamber.
Pretty old school technology. It's been around for many years
I have installed a few and have had great success. You can take a single condensing unit and make it of variable capacity. Very nice when you have problems with a single hooked up to several or more loads and your having issues. A little in depth to install but really nice control. The first one I put in was over 4 years ago and have not had one problem with it.