A heavy duty and extra large circular slide rule made most of metal comes in the original military color carrying bag. It was made for the Eastern Germany army for artillery calculations in the field. There are 2 cursers for easy handling and reading the different scales on both sides of the disc. It is complete, working and in great condition. It measures 28 cm or 11 inches in diameter. Check the attached video on how to work your vintage man tool : slide rule operation instructions!