This pattern is a general imitation of a small fish or sub-surface insect (e.g. corixa) with its silver body and dark thorax. It has a gold bead at the head and with the slim body, this helps in getting the fly down to the fish. It can be fished with floating lines (+ long leaders) or with intermediate or sinking lines. It is available in size 10, 12 and 14 on a D/E hook.