UPPER SCALE INDICATES PERCENT GRADE IN 5 PERCENT INCREMENTS FROM LEFT 45 PERCENT TO RIGHT 45 PERCENT; INDICATOR IS A FLOATING BLACK BALL INSIDE A CLEAR GLASS TUBE FILLED WITH DAMPENING FLUID IN FRONT OF A WHITE BACKGROUND; MATERIAL IS BLACK POLYCARBONATE; MARKINGS ARE WHITE SILK SCREENED; OPERATING TEMPERATURE RATING IS MINUS 50 DEGREES FAHRENHEIT TO 180 DEGREES FAHRENHEIT