If you fly, chances are, you've used a "universal" fuel tester just like this one. It works with most any aircraft fuel drain: both pin and petcock type. The transparent cylinder is 4.5" (11.4 cm) long and 1" (2.5 cm) in diameter with octane color-coding molded in the side. Also included is a screwdriver blade with both Phillips and slotted heads (for removing airplane cowlings).
