An isothermal clock device for mechanical and/or functional components of a watch, the device being provided with a bracelet and a casing including an enclosure wherein a case of said watch is capable of being arranged and a reversible fastening device fastening the case of a watch in the enclosure of the casing by keeping it away from the set of elements of the casing defining this enclosure, the fastening device including at least two connecting members each connected to an attachment area of the case from at least one telescopic bar.