One end is open-ended, while the other is a ring spanner. This makes them adaptable to all situations. But it is to say that because they are not adjustable, they can work for only a specific size of the fastener, as both the profile heads are of the same size.
Combination spanners are used for assembling and dismantling structures. for example, for setting up pieces of furniture (bookcases, chairs, cupboards, etc.), users will need them. But this is not all they can do; they are used in a wide variety of tasks in industries such as manufacturing, automotive, repairs, decoration, etc.