Swaging tools are oblong shaped tools typically used to locate minor tight spots in the tubing string.

Swaging tools typically come with upper and lower thread connections so that additional tools may be ran below if so desired.

Swaging tools also typically come with a through hole and bypass ports so that the tool may travel more freely in a wellbore full of fluid.

Applications:

Swaging tools may be used to locate undersized or tight spots in a tubing string that may adversely effect tools such as bottom hole plungers, bottom hole pumps, or anything that may require a specific minimum tubing diameter to function properly. 

Swaging tools may be used in fishing operations involving slickline or wireline, these may locate the top of the wire or slickline and  allow for more precise fishing operations.

Swaging tools may also be used for swaging out minor tight spaces such as collars, or very minor pipe imperfections.