A cylindrical weight is what I would say is the ideal weight for a Carolina rig, and that would be its main purpose. Also obviously named because it is shaped like a cylinder, this style weight works well on a Carolina rig because it offers a lot of surface area for bottom contact.
When fishing a Carolina rig, maintaining contact with the bottom is key but that’s not always easy to feel in deeper water. With a bullet weight for instance, there’s less surface area of the weight coming into contact with the bottom and so you can’t feel the bottom as well. But since a cylindrical weight keeps better contact with the bottom, you can feel the bottom better to know not only that you’re maintaining bottom contact but also what type of bottom you’re coming over whether it’s soft, hard, gravel, etc.