ProMoly™ (4130) High Performance Mechanical Tubing is cold drawn in the United States of America and is produced to MIL-T- 6736 B (AMS-T-6736A), AMS-6371 and AMS-6360 standard. Not only are you getting a well made, sturdy product but also the best technical support in the industry. There are many reasons why the racing world loves the seamless ProMoly™ Tubing, which is produced in Rounds as well as Streamline, Square, Rectangle and other shapes. Chassis builders in particular choose Plymouth's ProMoly™ because it is tough, strong (seamless) 4130, strength the weight ratio, and preferred advantages in welding and overall performance.