The real McCoy?

     You know those old-fashioned drip oilers?  A cylinder of glass, clamped between two brass saucers, a needle-valve at the top and a threaded fitting at the bottom, with a nozzle and a little fiber plug so the oil goes drip, drip, drip at a slow and steady rate?  Found all over antique machinery, especially on moving parts where connection to a central oil supply would be tricky?  Common on steam engines?  Used for one of the folk entomology stories about where the phrase "the real McCoy" comes from, a "McCoy Company" being a supposed manufacturer of them?

     Amazon sells them.  A bunch of different kinds.