The Sanitaire Vac website sells a selection vacuum cleaners. The
Sanitaire is a range of industrial vacuum cleaners built by the
famous Electrolux company.
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The best place to start looking is
http://homeappliance.manualsonline.com/manuals/mfg/sanitaire/sanitaire_vacuum_cleaner_product_list.html.
They have a full range of User Manuals for Sanitaire Vacuums
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Sanitaire vaccums don't need a bag. Well, the answer to your
question can be quite expensive. There are options of bagless
sanitaire vacuums ranging in the mid $100's range.
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it's usually something to do with health or hygiene