Specially designed to provide extra grip on stainless steel tubing, Superseal fittings feature a collet with integrally molded stainless steel teeth similar to the standard Super Speedfit/push-fit design. They also incorporate an additional hand-operated nut and wedge-shaped plastic washer to apply extra pressure to the collet and the double o-ring seals. This causes the collet teeth to bite thoroughly into the tube to provide grip, while at the same time compressing the o-rings to further enhance sealing. This functionality makes Superseal ideal for potable liquids and other food quality applications that involve stainless steal tubing. You can use the SI range of inch-sized push-fit fittings with tube sizes 1/4 - 3/8 in. OD.