The Equalizer EQ2 Heating and Air Conditioning Register Booster helps boost up to 80% of air that has been heated or cooled from under-performing registers in your home. This register booster features a built-in temperature sensor. The booster is made of high-impact, ABS-polycarbonate with a flame-retardant housing. This register booster is an energy efficient way to improve circulation and comfort in your home.