The ARM1 is a precision, miniature instrument that provides an easy to read, real time indication of the air/fuel ratio of an internal combustion engine. It features a brilliant, 5-color display that is automatically dimmed for night viewing. It is an ideal monitoring tool for calibrating engine air/fuel ratio or making adjustments while driving.

The ARM1 is designed to operate with most stock narrowband oxygen sensors. Higher accuracy can be achieved by using it with the Split Second EGO1 sensor. The ARM1 can also be used as a display device for a wideband lambda meter that has a 0-1 V analog output.