The Challenger Series 4310 Pro Pak blower package from National Vacuum Equipment comes with a stainless steel noise-reducing acoustical enclosure. Thick polyurethane foam with a moisture- and chemical-resistant film covers the interior walls of the enclosure for noise absorption. The air ballast silencer is incorporated into the sound enclosure to reduce noise and overall size. The compact package requires 36 inches of frame space to mount to the truck. Systems are available in gearbox or hydraulic drive, with airflows of 540 to 940 cfm and vacuum levels to 27 inches Hg continuous. Packages come standard with a diesel flush kit. 800/253-5500; www.natvac.com.