Normal strings have hexagonal (hexagonal) core wires that simplify production and reduce manufacturing costs. Round core wires, on the other hand, have to be wound with the utmost care to ensure even pressure on the nickel wire, which leads to a very long vibration of the string (sustain) and a uniform tone development.
Please note: The wrapped strings cannot be simply cut because the nickel wrapping would immediately dissolve. Therefore first make a sharp, right angled bend into the string and then trim the string behind the bend.