The natural foreskin has three principal components, in addition to blood vessels, nerves, and connective tissue: skin, which is exposed exteriorly; mucous membrane, which is the surface in contact with the glans penis when the penis is flaccid; and a band of muscle within the tip of the foreskin. Generally, the skin grows more readily in response to stretching than does the mucous membrane. The ring of muscle which normally holds the foreskin closed is completely removed in the majority of circumcisions and cannot be regrown, so the covering resulting from stretching techniques is usually looser than that of a natural foreskin. Nonetheless, according to some observers, it is difficult to distinguish a restored foreskin from a natural foreskin because restoration produces a "nearly normal-appearing prepuce."