Abstract: An air deflector for use with an air register of the type commonly found in residences, has a rectangular sheet of flexible material with two opposing edges folded in the same direction to form a flange along each edge. The sheet has sufficient rigidity so that the folded position is maintained and the deflector has an inverted U-shaped cross-section when mounted on the register with one of the flanges placed along each side. Magnetic material on the flanges holds the deflector in place on the register.