SUR-FIT Natura Urostomy Pouch - The SUR-FIT Natura ostomy system is a comprehensive product line with our latest skin barrier technologies. The plastic coupling ring allows the pouch and skin barrier to snap together for audible security. People living with a urostomy have unique needs, which is why ConvaTec offers a pouch product line especially for them. SUR-FIT Natura urostomy pouches have an extended anti-reflux valve, comfort panels and a choice of two types of drainage taps.