This is a set of 4 Evah Pirazzi double bass strings. I used them for about 3 years, but I replaced them because I wanted to try Spirocore strings. I used them for an average of 3 hours per week. They respond well and have a soft, warm sound. They are also loud and easy to handle, so I recommend them to those who are tired of Spirocore strings. No returns or exchanges, please.