2 Piece Colostomy Systems allow you to change the ostomy bag without having to remove the baseplate or skin barrier. Two Piece Ostomy Systems consist of a skin barrier (also called a flange, wafer or base plate) which attaches to the stoma and snaps together with the ostomy bag through a plastic flange. The skin barrier protects the skin and funnels waste to the ostomy bag that collects and stores the waste. Additionally, these bags are easy to apply and remove, and should be replaced approximately every two to five days; the skin barriers should be replaced approximately once or twice a week.