Teng Tools Flare Nut Wrenches are ideal for gripping the nuts on the ends of tubes, for example in automotive and plumbing applications. They have a narrow opening, just wide enough to allow the wrench to fit over the tube, and thick jaws to increase the contact area with the nut. This allows for maximum contact on plumbing nuts, which are typically softer metals and therefore more prone to damage from open-ended wrenches. This double flare nut wrench has different sized openings at each end. The heads are angled to allow better access. Made from chrome vanadium steel, it is strong and durable. Manufactured in accordance with DIN 3118 standards Satin finish. The TEN641213 Flare Nut Wrench has the following specifications:Head sizes : 12 and 13mm.Opening sizes: 9.0 and 10.3mm.Length : 178.6mm.