By The London Nameplate Mfg. 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 with a 1936 serial number. Predates the more commonly found MK.II & IIA. Lovely condition. Stock code M21821.