14mm or 18mm female/female bong, bubblers and water pipes connector, it is now available at alchimiaweb.com
Pipe and fittings connectors
These borosilicate adapters have two female mouthpieces where to connect a glass pipe or a bubbler male of the same diameter.
You can use the 14mm female/female connector with for example a Quartz Banger XXL DC Glass Glob Stopper in a Bubbler Bio Capsule Ratchet.