For connection to any standard 12V DC powered system. This includes all digital door entry systems, the BSX isolated exchange system and systems combined with keypad or proximity access control. This model replaces previous telephone models - BS-LX, 500X and 500LX. The XL5-LX is the new audio handset from Bell, with a new contemporary design, manufactured in white high-impact ABS plastic. The XL5-LX replaces the BS-LX & 500LX handsets.