A symbol used in fishing for sizing leaders and hooks, although the sizing methods of the two are not related. Leader symbols range from 0X (to distinguish zero from “O,”) to 7X (sometimes larger numbers). The larger the number, the lighter pound test and finer diameter of the leader. While exact pound tests will vary with the manufacturer, 0X is often around 9- to 11-pound test; 7X is about 1- to 2-pound test. Hook sizes also are based on an unrelated “X” system. Each hook style comes in a standard shape, length and hook wire size. X also denotes “power” of optics, as a 7-power (7X) telescopic sight setting/7-9X scope.