It is not a question of "twin bells" but a doorbell ONLY. The two bells are from the same seller and as the "2x twin bells ...". The rest sounds are poor and not too inspired: the same "songs" you can find on a mobile phone low end and only one or two "ding-dong". The frequencies (especially the media) hurt balances and offer something slightly garish. But at this price you can not qualify for exceptional quality. All the same I would not recommend it to people anxious or overly confined spaces. I returned the product (I tried two bells ...) and Amazon to accept immediately refund. Another reviewer expressed a difficulty of insertion into a socket with protective "earth". This is true even if there are possible solutions.
