They have been my go to mark of strings for at least 20 yrs. The very first set of strings I bought in Hawaii got home and opened and were tarnished and useless due to the old style paper envelopes and Hawaii humidity. After that, I bought D's and never strayed. Curiously, the only other strings I use are the usually hated and derided Fender Bullets on my Strats. The engineering makes sense to me.