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Kanger rubber O ring
mini o-ring (external diameter=12.8mm/L=1.9mm)for mini protank 2&3, areotank mini
protank o ring (external diameter=16.5mm/L=2.2mm) for protank2$3 , aerotank
The rubber o-ring for connection of top and glass or connection of glass and base, that's Top O-ring and Base O-ring, it also called seal ring