Shoulder strap loops are spaced up to 58 cm apart to fit a wide range of violin cases, ukulele boxes, and light instrument cases. Dual use design: this pack supports versatile use with a cushion on a hard shell bag to increase back comfort. Compatible with violin cases of various shapes, ukulele boxes, and other light instrument cases for convenient storage and transport. Provides space to store music scores and other small items, keeping essentials organized and accessible. Use scenarios: Musicians on the go: attach to a violin case or other light instrument case and carry scores and small accessories together. Travel or practice sessions: pair with a cushion on a hard shell bag to improve back comfort during longer wear. Music lessons or tutoring: use as a compact organizer to keep sheets, notes, and small items within easy reach while moving between rooms or studios.