For me, it already has problems at 2 cm sometimes, but I have mounted a small ramp bar at the problem areas. Now it works... I think the description says 2 cm.

So he will probably have trouble with 3-4 cm. Officially he can manage 2 cm... However, it has already driven onto/over a table leg that is approx. 3 cm - so theoretically it could manage higher heels. However, it can happen that it touches down and gets stuck on the threshold. With a threshold of 3-4 cm, however, you will have problems with pretty much every robot vacuum cleaner. As a rule, they can only manage 2-2.5 cm high steps.