BASETech is a common remote sensor for weather stations. They are sold as Basetech WS-9130-IT, TFA Dostmann 30.3147.IT, Techno Line TX 35-IT and more brands.  Although it should be able to survive on its own, a casing might prevent problems with humidity. The lid is fastened with just one screw, preferably a parker (diameter 3,5 mm) because there is no thread in the hole.