What type of rods produce a large curl pattern on either side and a smaller curl in the center?

Concave rods are designed with a unique shape that allows for a particular curling effect. These rods are narrower in the center and wider at the ends. When hair is wrapped around concave rods, the result is a larger curl pattern on the ends of the hair and a tighter, smaller curl in the center. This design creates a dynamic and voluminous curl that is visually appealing, providing varied curl sizes along the hair strand.

The structure of concave rods is what sets them apart from straight rods, which produce uniform curls, or spiral rods, which create consistent spiral curls throughout the entire length of the hair. Wide rods, on the other hand, are typically used for looser curls, and they do not provide the distinct curl variation that concave rods achieve. Thus, concave rods are the ideal choice for creating the described large curl pattern on the sides and a smaller curl in the center.