This month's item is a valve grinder (often referred to as a lapping tool). It's used to grind the seat of the valves in an engine. Later versions contained a small rubber suction cup at the end (as opposed to the metal driving point shown here). To get a better, more-detailed explanation of lapping, click here.

This item, which originally sold as the Sioux valve grinder, was manufactured by Albertson & Company, established in Sioux City, Iowa, in 1914. Today, the company does business as Sioux Tools. To enlarge the pic shown, click here.