The end chamber O-ring for Trojan UVLogic reactors, listed for the AS, AM and AL models (including the 08AS). The end chamber is the housing at each end of the reactor through which the lamp and quartz sleeve assemblies pass; this O-ring is what seals that joint against the treated water. It is a pressure-boundary seal rather than a cosmetic gasket, so a perished or flattened ring shows first as weeping at the end plate and then as a genuine leak under working pressure. Renew it whenever the end chamber is opened — the ring takes a compression set against the sealing face and will not reseat reliably a second time once it has. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.