HF1 series reverse osmosis membrane element low energy high efficiency The highest rated, most reliable membrane on the market! 2500 GPD 4.0" x 40" to fit standard commercial membrane housings Individually tested, highest rejection rates, long life Low energy, works on lower water pressures 150 psi or above Axeon commercial membrane HF1 4040 4.0" x 40" 2500 GPD HF1-4040