ConvaTec SUR-FIT® Natura® Stomahesive® Cut-to-Fit Wafer without Tape Collar 4" x 4" 1" to 1/2" Flange, Two-Piece Barrier 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. Stomahesive® skin barriers are ideal for people whose stoma output is semi-formed to formed. This reliable skin barrier provides a unique formula that enables the skin barrier to adhere to both dry and moist skin. It is gentle on skin yet holds firmly.