What is the name of the wrench that has a swiveling serrated jaw and a knurled control knob located between the frame and handle?

The wrench being described is commonly known as a Stillson wrench, which features a distinctive design that includes a swiveling serrated jaw, perfect for gripping irregularly shaped objects or pipes securely. The knurled control knob positioned between the frame and the handle allows for easy adjustment of the jaw's opening, enabling effective gripping without slipping. This design makes the Stillson wrench particularly effective for plumbing tasks, such as working with pipes, where a firm grip is essential.

In contrast, a pipe wrench is similar in function but typically does not have the same adjustable features and is designed primarily for gripping and turning pipes. An adjustable wrench, while also adjustable, features parallel jaws and is not specifically designed with a swiveling jaw or the same gripping capabilities tailored for rounded surfaces. A torque wrench is designed for applying a specific amount of torque to fasteners rather than gripping objects, making it a completely different tool with a different function.