Place Supply Guru’s Air Conditioning Foam Seal Strip on the top of your unit and lower window to seal out drafts, insects, and dust. Supply Guru’s Air Conditioning Foam Seal Strip is extremely resilient, easy to install, and protects against vibration, noise, and odors. Use to seal gaps between window sashes or between your window sash and air conditioners. Made out of highly compressible, open-cell, polyurethane foam.