Inner foreskin is mucosal tissue that extends from the glans to the ridged band in an intact penis or to the circumcision scar in a circumcised penis.

Along with the outer skin, the inner foreskin normally covers the glans of the flaccid intact penis.  It begins at the mucocutaneous zone and ends at the sulcus.  During circumcision, some, and possibly much of the inner skin is removed, along with the ridged band and most of the Meissner's corpuscles.

This mucosal tissue is very delicate, much like the lining of the mouth or vagina and is particularly sensitive.  It is full of nerve endings that respond to stretch, pressure and temperature, providing much of the pleasurable sensations during sex. The glans does not secrete moisture, but instead depends on this wet, mucosal tissue to provide the needed moisturizing, lubrication and important anti-bacterial protection. 

Non-surgical restoration can expand the remaining inner skin, and ultimately restore full coverage to the glans. The expanded mucosa skin lacks the original ridged band and most of the Meissner's corpuscles, but typically becomes moist and highly sensitive to touch.  The new inner skin also allow the glans to de-keratinize, also improving sensitivity.

Image Source:  www.infocirc.org