Stores ref. 13/44. 'Capt. Field's Improved' boxwood parallel rule with brass fittings. This is the less commonly found small version of the rule. Approx. 30cm/12" in length x 6.5cm/2.5" wide when closed. Air Ministry and crown markings. Some minor chips at the edges and loss to upper left corner. (see photos). Slight warping so does not lie completely flat. As used by the Navigator for route plotting in bomber aircraft. Fair used overall. Stock code M20292.