Spanner Wrenches, which are also known as Hook Wrenches, are used to adjust parts of the your coilover.
Different brands use different sizes of wrench, the sizes depend on the diameter of the shocks and locking collars.
Some brands have different will have two different sized locking rings, as one is used for a spring seat, which means it will likely come with two different sized wrenches. If your wrench breaks or gets bent, the replacement cost can range from approx 15-45$.
The locking rings can move up or down on the threaded body, and these wrenches are what allow us to torque them when setting the spring pretension or setting a ride height with the lower mounting bracket.