Also called tubular box or box spanners, tube spanners are useful for plumbing jobs. They are built using metal tubing, which often comes with two profiles at the end of both tools.
To use the tube spanner, you need to cover the entire head of the fastener. You also need to make sure that the wrench makes contact with all the sides and corners before you turn. The profile of tube spanners is quite specific. Therefore, you need to know first what type of fastener you are working with; otherwise, you may not be able to use it on the fastener.
Most tube spanners have a hexagonal profile, though. You will find that they are easy to pair with a fastener since a hexagonal type is the most common fastener profile. Tubular box spanners come in different sizes, which are in metric and imperial across flats (AF).
Note that you will need to use a Tommy or T-bar to turn the spanner. You will need to fit the bars through the holes, making sure that you are at the right angle. Choose a tube spanner set, so you have a variety of sizes and types when you need them.