We couldn't help but add the Jenerates Knitting Ruler to our tool box. This neat little tool comes in centimetres or inches and this version exclusive to us here at With This Cloth.
The ruler starts at zero at both the inside and outside corners, which means you can use it whichever way best lets you see your work.
There's a needle gauge from 2mm to 8mm, and the ruler fits a standard size tension square exactly.
Made in the EU in 4mm cherry wood veneer, finished by hand (by Jen!) with natural wax.
More information on the Knitting Ruler page over on jen's website here.