Cabochon Ruby is a signature glassware piece from the ADA premium line. Serving as the check valve, it prevents water from seeping into the Co2 regulator at night time when the co2 is turned off. At night time, water creeps into the tubing from the diffuser in the aquarium when there is no gas flow to prevent water seepage. The check valve prevents said water from damaging the regulator and is a necessary part of your Co2 system.
Plastic check valves also prevent water from seeping into the regulator at night with great effectiveness, however due to their nature, they tend to degrade over time, becoming less effective and needing replacement about once ever 4-6 months. Cabochon Ruby’s design ensures durability over the lifetime of the aquarium, because it is constructed using a mineral close to ruby (where it gets it’s namesake), therefore you never need to replace the check valve.