Stoma products are divided into one–piece system and two–piece system. One-piece system consists of a skin barrier/wafer and pouch joined together as a single unit. Provide greater simplicity than two-piece systems but require changing the entire unit, including skin barrier, when the pouch is changed. Two-piece system allows changing pouches, while leaving the barrier/wafer attached to the skin. The wafer/barrier is part of a “flange” unit. The pouches include a closing ring that attaches mechanically to a mating piece on the flange. A common connection mechanism consists of a pressure fit snap ring.