This slide rule is another offspring of the rule developed ten years earlier earlier by William Orr for the Connecticut State Office of Civil Defence. The M-2 Radiation Calculator was developed for the Radiological and Chemical Defense Service of the New York State Civil Defense Commission. It was copyrighted in 1964 and was manufactured by Wade Products Inc. of Fifth Avenue, New York.
It is 5 inches in diameter and made of plastic.
Given the exposure rate (rads/hr) at a given time after a nuclear detonation the calculator can be used to predicts the exposure rate at any other time. It can also estimate the radiation exposure of personnel who are in the area at some time after the explosion. The back of the slide rule has the instructions (bottom photo).