Size: 30 mm / approx 1 1/8 in. Hook: J:son SS.DF #10 Popular in many european waters, especially when fishing for rainbow trout during autumn. However, craneflies are found around the world within the northern and southern hemisphere. We recommend that you use a J:son Swivel for all your fly fishing, no matter what type of fly you are using. However, it is necessary to use a J:son Swivel whenever you fish a size 1 or 2 J:son fly.