It's a proto ruler, there are lots of proto rulers... This one has cm, mills, via holes with max current, text style and ration, copper thickness, basic layout footprints, mil to mm conversion, trace width vs max current, mm units, and visual trace reference.. Put another way, it has everything I need.
As an aside, I ordered the one made by the other reviewer on the same day I ordered this one.
Jan 13: Both ordered Jan 16: Both shipped to the u.s. (this one with tracking, the other from france with no tracking) Feb 6: This one arrived (exactly 3 weeks)
Still waiting on the one from france, and no way to track it...