What is commonly referred to as the rattail file?

The rattail file is commonly known as a small round file, which is used for smoothing and shaping the inner contours of holes and for detailing work on various materials. This tool gets its name from its long, narrow shape that resembles a rat's tail, making it ideal for precision work in tight spaces. The small round cross-section allows it to reach into areas where larger files cannot, making it invaluable for tasks requiring fine detailing or the removal of sharp edges in metalworking, woodworking, or other fabrication processes.

In contrast, half round files have a flat side and a curved side, best suited for smoothing rounded surfaces but do not share the same specific shape or functionality as the rattail file. The cross file is designed with a cross-hatched pattern for effective material removal but is not round. A flat file, as the name suggests, has a flat surface and is generally used for creating flat surfaces and edges. These other types of files serve different purposes that do not align with the specific functionality and design of the rattail file.