This is a nifty tool from Knit Pro. It combines a needle sizer with a gauge counter.
The needle sizer goes from 2mm - 12mm (US #0 - #17). The gauge counter consists of a clear window which has a red line in the center which measures 4" on one edge and 10cms on the other. You place this window over your tension square and, if it fits the red line, then you are spot on!
These are packaged individually.
Please click on the thumbnails to enlarge the views.