Single bundles refer to a single unit of hair extensions or weave, typically consisting of a weft of hair that has been sewn together at the top. Single bundles can vary in length, texture, and color and are often used to add volume or length to natural hair. Single bundles are usually made from human hair, with some synthetic options available as well. The hair is typically sourced from a donor or collected from a hair salon, and then cleaned, treated, and wefted together.