The Gas Stopping Station is a high-to-low energy converter for the exotic ion beams produced at NSCL. The beams are produced in the A1900 fragment separator and transported to the N4 vault where the gas stopping station is installed. The very fast ions arrive with slightly different momenta and are dispersed by a magnetic dipolar field onto a solid degrader. The degrader is wedge-shaped so that ions with a higher momentum go through a thicker section and are slowed down more than those with low momentum. The energy spread from the nuclear reactions that made the ions can thus be compensated (range bunching). The low energy and uniform beam is then refocused onto the entrance window of the gas cell. The ions then slow down and are thermalized in a chamber filled with 1 bar of ultrapure helium. The stopped ions are then drifted to the end of the cell with electric potentials and forced out as the gas flows through a supersonic nozzle. The ions are captured as they enter the lower pressure region by RFQ–ion guides Such devices use alternating electric fields to transport the ions with high efficiency through a series of chambers with successively lower gas pressures. These chambers make up a differential pumped system. Finally, after nearly all the helium gas has been removed, the ions are accelerated to an energy of 5-10 keV and are transported through a concrete shielding wall to the experimental area in the N4 vault extension (LEBIT Room).