These exercises are based on the Harmony that is suggested when the Major and Chromatic scales are juxtaposed.
There are 21 exercises per key-hence 252 exercises! (12 keys x 21)
Some feature contrary motion, others feature groups of 3, 4 ,5 , 6 ,7, 8, 9 notes. And others are rubato with wide leaps of range.
The Pdfs contain versions that are suitable for Sax, Flute, Clarinet, Trumpet
Piano, Guitar and other instruments. Some of the keys have high and low versions to accommodate the different ranges and abilities.
Some of the exercises are featured in this video: