The skin Barrier (wafer, back plate) is fitted first then the pouch (bag) is fitted to the landing area of the wafer. The method of attachment to the wafer varies between manufacturers – one method being press-on/click “Tupperware” type fitting, and the recently introduced “sticky” adhesive mounts.
The two-piece arrangement allows pouches to be exchanged without removing the wafer; for example, some people prefer to temporarily switch to a “mini-pouch” for swimming, intimate and other short-term activities. Mini pouches are suitable for minimum usage only.