Your furnace or air conditioning system may be sucking in deadly gases (carbon monoxide, radon, etc.) as well as dangerous chemicals, allergens, and pet dander. 

The Department of Energy Says - "Cover/seal furnace filter slot to eliminate air leaks."

The FilterLOCK is placed over the filter slot (or any seams in metal ductwork) to eliminate the entry of unfiltered air into your forced air system.  Millions of homes have open filter slots needing FilterLock to seal, save energy, and improve indoor air quality.

FEATURES: 

• Year round savings and protection
• Blocks allergens and pollutants
• One-size-fits-all standard air filters  - comes with two seal pieces that overlap
• Easy-on  / easy-off (reusable)
• Magnetically attaches to metal duct
• Saves energy - reduces utility bills

• Dimensions - 4-3/4" Wide - Covers slots up to 25" Long