Abstract: In a multiple stage boom including a base boom and a plurality of relatively extensible and retractable boom stages, a system for displaying the load rating information relative to the boom includes an angle measuring assembly and a color coded boom and chart assembly. A plurality of separate markings are provided on and spaced from one another along the length of an intermediate boom stage of the boom in such a way as to be sequentially revealed when the boom stages are extended from a retracted position. Each of the markings are representative of the length of the boom at the point of extension of the boom where the marking is first revealed on the boom. A plurality of color sections extend along the intermediate boom stage, each of which is provided between a different pair of the markings and is colored differently than the other color sections to provide visible confirmation of the distance of extension of the boom.