The EMG 57/66 and the EMG James Hetfield het set both have exposed pole pieces. In my opinion a much better sound than the 81, way crunchier/tighter low end. I am also pretty sure the 57/66 is the het set for people who do not want to endorse James. They use the same magnets have almost the same description the 57/66 came out a couple months after the het set. Either way great sounding pups, best they have made imho