The brand I use is Accu Gauge. I believe that is the name. Suppose to be certified to be accurate within, I don't remember, but a low %.
My experience with pencil gauges is not good. And you get what you pay for.
as used on Race Tech site
rode 07 Black Cherry VTX 1300R
States+DC & 11
i,both w/aux tank & Race Tech SuspensionIBA:Mile Eater Bronze &Silver,SS3000,3xSS2000,EclipseSS1000Gold, 19SS1000,6xBB1500,3TX1000,NPT 29/76; Lake Superior Circle Tour
15 to 20K per yr between the two MCs