That revolutionary strings, certainly more expensive, which provide additional richness to the sound in the midrange due to cobalt which is already justifies the extra cost. But they are still bluffing it's longevity compared to ropes "classic" ernie ball for power, they oxidize considerably slower, I hold in good condition at least 6 months without ever passing fast freight top , so even more with a flick of fast freight. Feel free this range is exceptional, LONG LIVE THE COBALT!