It's a OIL/GAS MIXING MEASURE CYLINDER FOR 2-CYCLE ENGINES. It's
exactly like the adjustable measuring cups that Alton Brown (and other
chefs?) on the Food Network uses. I'm sure that the same company that
makes these also makes the one for measuring oil for gasoline.
It's clear, with a sliding plunger that you adjust to the line for the
oil/gas ratio you use. It is calibrated for US and Imperial gallons.
The one I have was sold by Sears, Roebuck and Company many years ago.
They don't have them anymore, in fact no employees remember them.
Does anyone know of a source for buying these??