As previous speakers have already said, 2 cm max. We have more like 1 cm thresholds and even then it needs several attempts and only gets over with a lot of bumping and banging. Otherwise, the robot is absolutely fantastic for the price. On the quietest setting, it takes an hour to sweep an 80 m2 flat and picks up all the dust, hair and crumbs except on carpets

3 cm is too high and if so then only by chance and the threshold should be round

No, up to 2cm is just fine, even if the threshold is rounded, 3cm is too high