A 2-stage snow blower has both an auger that collects the snow and a high-speed impeller that throws it into the expulsion chute. This two-step process provides much more power and allows the machine to throw snow much further. 2-stage snow blowers also feature a self-propelled transmission that makes the unit easier to handle. 3-stage snow blowers include an extra auger to better break up ice and frozen snow. A single-stage snow blower does not have a transmission or fan: the auger collects and throws the snow out of the chute all in one motion. This makes single-stage throwers better suited to lighter, less compacted snow.