Adding weight to a tube fly is easy with the Aqua Flies cones. These cones are made of brass and are designed to fit the 1.8mm tubing. The cone can be held in place by inserting the 1.8mm tube through the cone and leaving about 1/16" extending out the front of the cone. Take a lighter and hold the flame close to the tube with out lighting it on fire. The tube will melt and form a collar in front of the cone.