FilterLock® by AllergyZone stops dirty, unfiltered air from entering your home through an open or poorly sealed air filter slot/door on your heating and air conditioning system (HVAC). FilterLock® works with any 1" air filter. Eliminating air leakage at the filter slot can improve air quality and reduce energy consumption. FilterLock® is re-usable and extremely durable. The patented, one-size-fits-all product installs in seconds without any tools and there are no sharp metal surfaces to be concerned with. Built-in magnets hold FilterLock® firmly in place. FilterLock® is used by homeowners, heating and air conditioning contractors and energy auditing professionals to enhance HVAC system integrity and improve the performance of 1" air filters.