Light weight, free swinging bobs that your young will not shy away from. Create any size trap you chose and build it yourself. All you need is four pieces of wood cut to the size you need. Each bob is 12 inches long, and the top, where the rod slide through is 2 inches across. The holes in the top are for a .1875 inch rod. If you wish to lock the bobs in the up position, screw in a cup hook, one each side at the hieght desired and run a rod through each cup hook which will hold all the bobs in the up position.