The vacuum can use the same compressor as the Air Knife, as long as the compressor size is not less than 100 psi/175 cfm. Nozzles at the inside bottom of the suction tube direct the air stream upward, creating a vacuum at the tube entrance so as to suck crumbled soil, gravel (up to 2 3/4 inch), and/or water from the excavation. The materials travel up the tube, and are deposited at/near the end of a 3.5" or 4" flexible discharge hose. The diameter and length of the discharge hose are determined by a combination of compressor rating and customer preference.