The MFF5 an Extra Heavy Duty Middle Frame Fitting with one leg and 5" leg and top-rail, designed to fit schedule 40 5" pipe with a 5 1/4" ID and 5 3/4" OD. The set screws are 12 millimeter and can be tightened with a 10 millimeter Allen wrench. These fittings are constructed with heavy-duty welding and are much stronger than aluminum. While this product should last up to 5 years in optimal conditions, harsher conditions may require replacement sooner. Sold individually. Parts List 1 - Middle Frame Fitting 6 - Set Screws Colors: Green