• Sealing air leakage/by-pass at the filter slot/door forces dirty air to travel through the filter instead of around it

• Reusable overlapping 2-piece design works with any brand 1 in. air filter up to 25 in. L

• Filter lock has built-in magnets which hold it securely to the metal duct work

• Installs in seconds without the use of any tools

• ENERGY STAR identified air leakage at the furnace and filter slot/door as 1 of 4 major problems with duct work

• FilterLock satisfies the department of energy recommendation that the furnace filter slot be covered to avoid air leaks