The Ox-class tug carries a drive field stabilizer that allows a fleet to reach a higher burn level. It's rare to see more than one or two of these in a fleet, however, due to prohibitive fuel consumption and high maintenance costs.
The Ox tug is an utility vessel that increases the strategic map travel speed of all ships (burn level) in its fleet with its Drive Field Stabilizer. Each tug increases the travel speed of the fleet by one burn level.
The Ox has a base sensor profile of 260 which is extremely high, much more so than the 150 sensor profile of even a capital ship. New players in particular need to be aware that while excellent for strategic speed it will also attract the attention of a lot of fleets. Fortunately the Ox has enough OP to also mount the Insulated Engine Assembly hullmod, bringing its sensor profile down to only 130.
It is important to remember that fleet speed is limited to the speed of the slowest ship in that fleet; given their huge logistical costs, multiple Oxen are best used to speed up many slow ships. In the case of one or not many slow ships a player may consider installing Augmented Drive Field on the slowest instead.
Ox-class Tug can increase fleet's speed beyond its own burn level of 8 - there is no restriction on a Drive Field Stabilizer's effectiveness, except a regular burn level cap of 20.