ToxBox is an air filtration unit that you insert in your furnace to prevent harmful particles and bacteria from entering and circulating in your home. ToxBox replaces disposable and highly ineffective 1-inch filters and catches more harmful air contents than other household furnace filters that are widely availble. ToxBox consists of a filter frame that is permanent and two filtration pads that should be replaced every 3 months. ToxBox is CSA-approved.