Combat Calculator

From the manufacturer:

The combat calculator is designed to be a replacement for the conventional combat resolution systems presently in use. The most common such system expresses the attacker's strength to the defender's strength in the form of an odds ratio with the outcome being determined on a combat results table by a die roll. The combat calculator accomplishes much the same purpose, however, it eliminates chance that is inherent in dice by putting the command decisions in the hands of the participants. Gone are the days when 20 to 11 was 1 to 1, now it is 20 to 11.

The combat calculator is a rare and obscure item produced in 1974 by Thomas Cleaver and Frank Aker.