Tug Type
The main purpose of this ship type seems to be to tow other vessels.

The tin opener (sorry, tug) appeared in only one episode, DS9: "A Time to Stand".  The schematic reveals that the "model" has almost no starship-specific details and is composed of whatever was at hand, including Intrepid-class warp pylons, Romulan warp nacelles, and clamps to fix a computer mainboard.