This filter will protect your Yocto-Meteo humidity sensor. It will prevent dust from entering inside the sensor and cause measurements drift.
A fair bit of warning: this filter will make your sensor a bit slower to react to temperature/humidity changes.
This filter is meant for the Yocto-Meteo (v1), the Yocto-Meteo-V2 already features an integrated filter.
It doesn't fit with Yocto-Meteo V2.
Waste my money.
@jae : the Yocto-Meteo-V2 doesn't need a Filter-cap because it already features a integrated filter (updated product description to make this more clear).