TRE - 4.5" Treadstone 90 Degree Aluminum Piping (AP45090)Treadstone Performance has introduced 90 Degree Aluminum Mandrel Bend Piping. A new line up of quality universal aluminum bends for your piping. In the past we have come across many manufactures and shops across the internet selling low grade Piping, that either you can not weld because of the poor quality, have a clear coat on them which makes welding terrible, are easily scratched and dented because they are so soft, or are made from recycled