D'Addario Orchestral Bulk 10-packs are the perfect solution for rental fleets and repair benches. They may not be used for resale purposes. The Kaplan Non-Whistling E string is specifically designed to solve open E-string "whistling" occurrences. It produces a warm, rich tone that blends very well with lower strings. Includes one free Kaplan Solutions Ball End Adapter for use on single hook style fine tuners.