This round slide rule is marked ALRO Militaire Rekenschijf (army circular slide rule). Made in Holland in The Hague and issued to the Dutch army, printed ALRO and MvO (Ministry of War) on the inside case flap it also shows the year 1953. Meant for the artillery to quickly calculate angels of fire specifically for mortars and other large artillery fire. High quality build with metal ring on a very thick black early plastic back ground with yellow inlay (explanation on use). In good working condition with minimal signs of use and age only, fully functional. It comes the original heavy duty leather case that is complete and in very good condition as well. It measures ca 13 cm or 5 1/4 inches in diameter. Check the attached video on how to work your vintage man tool : slide rule operation instructions!
