This 30 cm or 12 inch slide rule was made in England by the Blundell Company. It was specially produced for easy calculating of angles to shoot artillery for the military. It is also signed for this purpose on the back as the Artillert 10″ MK. 3 version from ca. the 1960’s. It is from the Omega range with clear A,B,C,D scales on the front and S, ST and T scales on the back of the slider. It is in overall very good condition, no warps, no chips, no discoloration. The cursor is fine as well. It does not come with a sleeve, just the rule. Check the attached video on youtube on how to use a slide rule!