Hydrofarm  MY1M25 25-Foot by 4-1/2-Foot 1 Ml Reflective Metalized Film
Reflective Film can give your plants an extra boost of light without using any more electricity. Reflective Film is extremely reflective material and is especially useful in those dark corners. Just hang it on the wall with thumb tacks or tape and there will be a visible difference in the brightness of your grow room.