Chromatic scales are an essential skill to master for any keyboardist. Within an octave range, there are 12 notes. This makes sextuplets work nicely for building chromatic speed (6 + 6 = 12). In this particular exercise, your two “target” notes are F-natural and B-natural. Every sextuplet run begins on one of these two notes. If you can visualize these two aiming spots, your accuracy will greatly increase.
When first starting, practice slowly and ensure that you are striking the correct notes. As you gain more confidence in your accuracy, gradually begin to push the tempo. Once you get to the exercise up to a bright tempo, you may want to repeat the last two measures additional times for added endurance.
For the extra motivated, you can transpose the exercise and learn it in all 12 keys.