lead shot
Is what is inside that tube. The one I recieved last year worked OK, but I never really had a major problem with my coil. If you hunt in salt water, the coil is much to floaty and needs the weight. A small sock with velcro sewn on each end filled with sand will work, and attaches and detaches fast. Using metal, like lead is ok, but needs to be secure to the shaft or coil so there is no movement....Gil