Carvin SERIE'S FEATURESModels of 14" (35,6 cm) 16 po (40,6 cm) 19 po (48,3 cm) 22,5 po (57,2 cm) et 25 po (63,5 cm)Upper distribution system integrated into the dial valve and engineered to direct water evenly across the entire surface of the sand – up to 25gpm/sq.ft. (61 m3/h/m2) without sand migration or channeling.7-way dial valve with "sight glass" automatic air relief, and pressure gauge. The 7 functions are :Non-Corrosive resin clamp for simple installation and service