This is a replacement sensor cage for the Vaisala HMP41/45 thermohygrometer. 

It's worth repairing if you have a legacy unit. The new replacement sensor masts come with integrated sensors rather than the older discrete components. The old sensors are much less prone to drift, fouling, & are more accurate at higher temperatures. 

To install this sensor cage, simply flush cut off the bars of the original cage & slide on this cage after applying a thin ring of either super glue or E6000 around the top of the sensor mast. 

I've also included the STEP file in case anyone wants to modify the model.