The twin-screw supercharger, at first glance, appears similar to a Roots supercharger, both inside and out. The two technologies are indeed similar, however there are significant differences. At the heart of the twin-screw supercharger are two rotors, or "screws" that rotate toward each other. The rotors mesh together and draw air from the back of the supercharger. Because the compression is done inside the supercharger, this design produces less heat than a Roots supercharger. In fact, it is almost as thermally efficient as a centrifugal design. Like the Roots design, the twin-screw is a fixed displacement supercharger (meaning that it pumps a fixed volume of air per revolution), and because the tolerances between the rotating screws are very tight, its ability to create boost at low rpm is unparalleled.