I have just recently read an article about the abilities of catfish homing in on sound and where one guy was using an old fashioned red and white bobber. These he prepared by drilling a small hole into the float then inserting a few #6 shot lead pellets then sealing with a bit of tape and crazy glue. This he placed on the leader between the bait and a pegged slip bobber. I have been entertaining the idea of giving it a try but will probably opt for a drop of silicone as opposed to the tape and glue.