From DR:

Hi-Beam stainless steel bass strings are round wound and constructed on a round core which makes them unique and also require more time to construct. This extra effort makes Hi-Beams a bass string that is highly flexible and musically but not harshly bright. They don’t eat your frets, are durable and have an unusually long life. HI-BEAMS are the string to choose for brightness, punch and ease of playing.

• The stainless steel wrap wire produces a balanced  brightness that cuts through the band

• The round core wire increases flexibility and musicality without making the tone harsh