Made in Canada by Ontario Hughes Owens Co. Ltd. Stores ref. 6B/108. Circular white metal instrument. Has rotating discs for setting the ground barometric pressure, temperature, indicated height and airspeed. For use with isothermic calibrated altimeters. Used by Navigators when plotting routes etc. Well marked early example. Predates the more commonly found MK.II & IIA. Super unissued condition with card issue box (different manufacturer). Stock code M20433.