scouter
A small, single-lens eyepiece that is worn wrapped around the side of the head, its name here originating from Dragon Ball Z. The device typically sports a heads-up display that provides its wearer with statistics or information on their surroundings, similar to a head-mounted display. Its most well-known feature, however, is its ability to calculate the power level of any living being, and displayed the result as a number.
Not to be confused with the monocle, another single-lens eyepiece used expressly for correcting vision like glasses.