What is the primary characteristic of barrel curls?

Barrel curls are characterized by their large center openings and the way they are installed. They are designed to create volume and structure in the hair, positioned in a standing position. This allows for a more pronounced curl that can add body and movement to hairstyles. The larger center opening of barrel curls supports their intended purpose of creating larger, looser curls or waves rather than tight, springy curls. The vertical positioning when securing the hair enhances the overall lift and provides a more dramatic effect in layered hairstyles.

In contrast, the other choices refer to different hair styling techniques that do not accurately describe barrel curls. Small center openings would apply to tighter curls, hot rollers are a separate method of achieving curl, and the idea of curls lying flat against the scalp typically pertains to techniques that produce a different curl pattern. Thus, the unique feature of barrel curls lies in their size and how they are shaped and positioned during styling.