An advancement in technology.
I heard, that when NASA astronauts checked the spaceships that came back from space, they found out that the structure of metals was changed. They had become stronger. The same technology is applied here. The strings are treated in extreme cold, and they are more responsive and somewhat stiffer.
I use these strings on my superstrats, to play in B standart tuning. In comparison, I use 12-68’ strings from other manufacturers, and they seem as tense as these blue steels. They hold up great, they sound really bright and so far, I haven’t broken any single one of blue steels strings.
If you use coated strings as I did and still do today, then I suggest buying a string conditioner, because these strings get dirty fast. I suggest cleaning these (and basically all) strings after playing, and they will stay great for a long time.
Note, that the first three strings are 13 to 26w, which means, you might have harder time playing solos. The fourth string is wounded, similarly as acoustic guitar sets, which gives more aggressive low end vibration, and tighter sound.