1 、可以避免出门忘带钥匙； 2、帮助记忆力不好的人提供方便； 3、父母提醒孩子的工具； 4、可移植性号；(First, through the voice prompt, can effectively avoid going out to forget the key, the door forgot to pull the key situation. You don't have to waste time with their families from far away and ra