Brightness and ease of playing.
Hi-Beam stainless steel bass strings are round wound and constructed upon a round core, which is unique in the industry. Hi-Beams require much more time, care, and extra steps to make than other bass strings. The extra effort DR expends making Hi-Beams results in a bass string that is highly flexible, musically bright (not harshly bright) and renowned for durability, unusually long life, consistency, and string-to-string balance. They don't eat your frets.
HI Beams 6 String Bass Medium .130 Low B (30-130) Specifications: