1/8" (0.125", 3.2mm) Cross-section, Black 83A Durometer Welded Endless Round O-Ring Drive Belt. This is the standard O-ring drive belt used on line-shaft and powered-roller conveyors.

This belt is identical to clear 83A, other than the color. Typical stretch is 10-15%.

Measure belts by their linear cut-length (middle circumference), NOT diameter.