If you are dealing with desiccated mummies I would not recommend an active system for the display cases. Reasonably well sealed display cases with a preconditioned humidity buffer (I recommend 35 x 5 %RH) will do the job. If it is a long-term display then I would go for hermetically sealed cases with an inert gas atmosphere (nitrogen or argon). Mummies that have not been desiccated will require different conditions, which can also be provided by passive systems. Frank D. Preusser