Question: what is the difference between mi band 3 and 3i?
Answer: In terms of power, Mi Band 3i packs a 110mAh battery that is claimed to last for two weeks straight. Mi Band 3 also has the same battery capacity. As for the Mi Band 4, it comes with a bigger 135mAh battery. All three fitness bands come with 5ATM rating for water resistance up to 50 metres.