This strong metal ruler has an end stop to aid accurate measuring of wing chords. It may be used to measure tails as well. This is a machinists' rule, with 1 mm and 0.5 mm divisions on one side, and 1/32" and 1/64" divisions on the reverse. The rule is made of stainless steel, with solid brass end stop. It is available in 15 and 30 cm length, and for right-handed (see the first two photos) and left-handed use (see the third photo).