You can insert a small battery to maintain visibility when fishing in the dark or in dim light. These floats have made night fishing so much fun and so much easier, and they give off enough light at night to be visible from a distance. EVA FISHING FLOATS: These fishing floats are made of EVA foam. Solid design, waterproof and corrosion resistant. They are easy to attach to fishing line and replace glow sticks. How do I place the float on the line? Attach a snap swivel to the line and attach it to the eyelet of the float. SENSITIVE FISHING FLOAT: These floats have great buoyancy, 3 buoyancy to choose from: 10g, 20g, 30g. The float features a 360 degree swivel at the bottom that allows the bobber to rotate 360 in the water and keep the line at the correct depth. They work great as slip poses. BRIGHT COLORS FOR DAYLIGHT VISIBILITY: The surface body has been painted with bright colors for daylight visibility. Wonderful tool for fishing lovers, high quality workmanship, works well at night, makes fishing more fun. Ideal for fishing for pike, perch, trout, zander, carp.