16MM 1.5 LPH (0.375 GPH) 16MM 2 LPH (0.5 GPH) 16MM 4 LPH (1 GPH) 16MM 8 LPH (2 GPH) 20MM 2 LPH (0.5 GPH) 20MM 4 LPH (1 GPH) 20MM 8 LPH (2 GPH)