Unfortunately, there is nothing written on the filters to indicate which model types they fit. I measured the filter and was able to order the correct filter.
This filter fits the 3H.
Unfortunately, I can't say whether it also fits other models.

Yes, it fits Xiaomi Mi Air Purifier 3H:
(https://www.digitec.ch/de/s1/product/xiaomi-mi-air-purifier-3h-44-m-38-w-luftreiniger-12307491)
Product dimensions (of the device):
24 cm length
24 cm width
52 cm height