RAF issue Aircraft Clock, Mk 2B
27. The clock Mk. IIB is fitted with a self-starting 8-day movement and is generally similar to the clock Mk. II but differs in the method of winding and hand setting. The bezel, in this instance, is screwed on, the clock is wound and the hands set by means of a knob which projects from the case at the bottom right-hand corner; the corner of the fixing plate is cut away for this purpose. This knob is spring-loaded and is knurled to facilitate turning. The clock is wound by a clockwise rotation of the knob and the hands are set by pushing the knob in to its full extent and turning it until the hands assume the required position. The knob returns to the winding position when released. Red painted dummy hour and minute hands are suspended inside the cover glass, and may be set by twin knurled knobs. The clock has no seconds hand.