This week's tool was commonplace at full-service gas stations during the 1950s to the mid-1970s. It was a sales tool used by the attendants to sell additional products in the days when you would get your oil, coolant and washer solvent checked with every fill-up. You might have also gotten a glass tumbler or a presidential coin for your patronage, too.

Dimensionally, it's four inches tall and three inches wide at the top. It's 5/8″ thick, but the black button at the bottom adds 3/8″ to the overall thickness. This button is depressed to move a needle on the scale, with graduations from 32 to 0 ounces. A similar scale on the back reads in the opposite direction so the exact measurement can be viewed from either side. The name on the tool was "Tel-Tale" but we have covered the rest of the etched text so as not to give it away too easily.

Directions are on a decal on the back that would give the identity away if we showed it to you. It has a manufacture origin in Gary, Indiana, if that helps you, and the back label also states that it is an "Official test indicator for the HVB." Can you tell us what the tool is, and how it was used?

This blog entry originally appeared on Hemmings Daily.