Thread rolling screws are a type of threaded fastener that forms threads that securely and reliably fasten into materials through pre-existing holes. Thread rolling screws form threads in material by pushing material outward. They are similar to self-tapping screws, but with a finer pitch and a thread form that is closer to that of a machine screw. The process of thread rolling involves extruding steel to form the threaded portion of a fastener, instead of being removed as in cut threading. In this process, a bolt is manufactured from a reduced diameter round bar. For example, a 1-inch diameter bolt is manufactured from a 0.912-inch diameter round bar. This “pitch diameter” material is approximately the midpoint between the major diameter (peaks) and minor diameter (valleys) of the threads. The bolt is “rolled” through a set of threading dies which displaces the steel and forms the threads. The end result is a fastener with a full 1-inch diameter threaded portion but a reduced body diameter of 0.912 inches. Roll threading is an extremely efficient process and often results in significant cost savings. Therefore, it is preferred over cut threading whenever possible.