A fishing swivel is a small device consisting of two rings connected to a pivoting joint. The device is usually made of metal, and the pivoting joint is usually ball- or barrel-shaped. The line from a rod and reel is tied to one end, and a length of fishing line, often terminated by a hook, lure or sinker, is tied to the other. The main purpose of the swivel is to allow the line to untwist during line retrieval, preventing undesirable tangling. This is particularly important for users of monofilament test line.
A secondary benefit of the fishing swivel is that it may stop a sliding sinker, which depending on fishing method may be placed before or after the swivel. Snap swivels have a safety-pin like clip linked to one of the rings. Lures may be affixed directly to the snap. The presence of the swivel has been said to detract from the effectiveness of some types of lures. Depending on the position of the lure, the hooks can become entangled in various ways with the swivel.
It is also noted that swivels can serve as weak points in the line, and therefore lessen the likelihood of landing larger or harder fighting fish. Three-way swivels provide a point of connection for an additional lure or length of line, and are essential for certain line and hook setups.
Fishing swivels come in sizes ranging from a few millimeters to several centimeters, and are traditionally either flat black or brass in color. More modern swivels can be obtained in lustrous red and blue varieties. It is somewhat possible that the swivel color plays a role in attracting fish, especially in low light conditions.