Usually the feed size range or the desired throughput dictates the selection of specific jaw crusher. The current trend is to go to the largest feed opening that is economically feasible in order to avoid as much secondary breakage as possible (Stansell, 2003). Once a crusher is selected it can be determined whether or not the crusher will provide the desired reduction ratio or product size distribution. As was noted previously the size of a jaw crusher’s discharge opening controls the product size distribution. Thus, determining whether a specific jaw can produce the desired product is dependent upon whether or not that crusher can have its discharge opening set to the required dimension.