Counterweight Water Cup?

[onafixedincome]

Some years back, I had a chance to use a water cup which had a small brass weight at the rear (the cup was white plastic); it connected to a water supply (rubber) hose. The principal was that as long as the cup was full, the tip of the portion with the weight was held up, blocking the water flow; when the cup was not completely full, the weight pulled the tip down, allowing water to fill the cup and then again blocking the flow.

Has anyone seen these around? I'd love to have them for my teensy little Serama chicks...! If I'm remembering correctly, they take up less vertical space and thus can be closer to the ground without winding up full of kicked up 'stuff' (I hope!)....

Help!