3/8" (1cm) hose to drip chamber connector
This connector allows one to plug 4 drip chambers (the hospital thing) into a water reservoir with a standard 3/8" hose.
Handy to provide drip irrigation to your flowers while you're traveling, or to just be able to fill the tank and forget it for a week or two.
The object comes with a cylinder that should be printed with a flexible material (I use ninja flex), so that it can be fitted in, and seals, the plugs.
The drip chambers are expected to have a 5mm diameter connector.
To be water-tight, the object should receive treatment with acetone if printed with ABS, heat treatment if printed with PLA.
More on how to use it at http://www.instructables.com/id/Drip-irrigation-3/.