It has two important characteristics, apparent only on erection:
- Penile skin tenses, stiffens and shortens, firming up the connection between shaft skin and ridged band. This change allows for the transmission of movement from the base of the erect penis to the ridged band.
- Penile skin undergoes a marked frictional change, brought about by stiff, forward-pointing skin folds. The mechanism is similar to that which raises goosebumps.
The changes in penile skin are brought about by contraction of the Dartos muscle. Between them, stiffening and frictionality ensure that the ridged band is instantly alerted to changes in position of the penis within the vagina.