I've recently discovered that many threads, no matter how they are stored, age poorly; they dry up and they fray. When I figured it out, I worked a test sample using each of my thread brands. K.O. is the only one that worked perfectly each time, even though it's the same age as the others. I could always thread the needle without splitting the thread, didn't have to treat it every five minutes, and wasn't on tenterhooks waiting for it to fray (it didn't). Whenever possible, I'm planning to buy K.O. when I replace a thread. I wish K.O. came in more shades, but that's my only negative. It costs more, but it's absolutely worth it; not only do I avoid frustration, I'm not selling a product that may unravel down the line. I like Fireline, but it's not always the right type of thread for a project. When it isn't, and the colors are right, I reach for K.O. thread. Happily.