Approximately 18.5 x 24.5cm. May 1946. Three sheets, printed both sides. Instructions for use and fitting of the H-type mask with details on sizing, adjustment and cleaning. It also covers the importance of the mask valves and use in very low temperatures. Illustrated with photographs and diagrams. Creased/folded with light soiling and corroded staples. This sheet was issued in the box with all new masks. Rare to find. Stock code P18091.