Nilfisk Advance Backpack Vacuum (Backuum) (01796934) (HEPA) Lightweight, ergonomic design to reduce fatigue (ergonomic study available) Low noise level for operator comfort and cleaning in noise-sensitive areas Upstream HEPA filter allows for safe collection of hazardous materials, trapping 99.99% of particles, down to and including 0.3 microns. Standard equipped with a sack-style main filter that will prolong the life of both the HEPA filter and motor. Exhaust air is directed upward so that it does not interfere with the operator.