This is a Pentair R172224X Black Drain and Vent Valve for High Capacity Automatic Feeders, Dynamic Series I, II and III Inline Cartridge Filters, Chlorine/Bromine Dispensers.
This valve is typically used with the High Capacity Automatic Feeder Models HC-3315, HC-3330, HC-3340; Dynamic Series Chlorine/Bromine Dispensers; Dynamic Series 1 Inline Cartridge Filter Model RDC-25; RDC-25S; RDC-50 and RDC-50S; Dynamic Series II and III Model RTL/RCF and Predator II Mini-Cellular Media Filter Systems.
