Ratchet spanner sets are often among the more expensive types of spanner kits, but their handy added functionality makes them easily one of the most popular designs found in both professional and enthusiast tool kits the world over.
The main advantage of a ratchet spanner over a non-ratchet or regular type spanner is that, where space for a full rotational arc is limited, they don’t need to be removed from the nut and realigned in between turns. The ratcheting mechanism allows for free rotation of the spanner in one direction but not in the other - this means you can tighten a nut clockwise, for example, and then pull the spanner back in an anticlockwise direction to begin another clockwise rotation without ever lifting it off the fitting.
Nearly all ratchet-type spanner sets will allow this feature to be deployed in both directions, either by flipping the spanner over or by adjusting a small lever on the handle or head of the unit. Spanner ratchet sets are usually sold in open-ended, flare or ring head configurations, depending on the types of fixtures you need to tighten or loosen.