O-rings to suit Onga & Balboa spa bath pumps. Suit these style (and these) unions. Approximately 50mm ID, 3mm cross-section.
Suits Onga & Balboa 2381, 2388, 2391, 2394, 2398, 2404 pumps, and others.
Note the photos of the unions are there only to show which fittings these o-rings suit.