Our exclusive SUPERLOK i-fitting tube fittings include the patented red ring gap gauge that make it impossible to over-tighten or under-tighten. When you have tightened your tube fitting nut to the correct depth, the red gap gauge rings pop off, letting you know you have done it correctly, leaving no possibility of error. These tube fittings incorporate a built-in gap gauge for safety and accuracy, allowing you to complete your projects with confidence. SUPERLOK Tube Fittings are produced by a strict management of materials, high precision design and the best machining technologies. SUPERLOK Tube Fittings tighten easily and are leak free under shock, vibration and temperature cycling. The use of SUPERLOK tube fittings result in additional productivity and cost reduction for the end user. The best interior surface finish in the industry reduces particle entrapment and improves the flow of fluids and gases.