This is a coventional 7- Roller Wire Straightener. This design has been tested by fire, so to speak, and has been in existence for over 50 years. The diameter of the rollers, and the size of the V-Groove determine what range of wire-diameter it can accomodate.The quality of the straightening is not quite that of it' s Mentor, the Rotary Straightener, but it doesn't lag very far behind, especially considering the price differential.