Kopprasch refers to the works of the German composer and musician, Kurt Kopprasch, who is best known for his studies for the trombone. His compositions, particularly the "Kopprasch Studies," are widely used by trombone players for developing technique and musicality. These studies cover various aspects of playing, including tone production, articulation, and rhythm. The "Kopprasch Studies" are often included in the repertoire of students and professionals alike, making them a staple in trombone education. They are designed to challenge players while also providing a solid foundation in essential skills, contributing to the overall growth of a trombonist's abilities.