Channel locks, commonly known as tongue-and-groove pliers, are used to adjust or hold nuts and bolts, or hold onto objects which are irregularly shaped.

What makes the tool effective is the design on the serrated edges. The jaws are orientated at 45 and 60 degree angles. This allows for the lower jaw to adjust for different sizes. For increased leverage, the handles are usually 9.5 to 12 inches long.