As far as I am aware, complete eta movements come packaged for retail sale in sealed, protective bags. These are absolutely perfect and need no work at all. A factory or a bulk buyer receives trays of eta movements in plastic clamshell cases which are not protective from humidity, dust, etc. So depending upon how you purchase your eta movements, the delivery method is very different. It is 100% upon the shoulders of the factory to then store the bulk trays of movements in a clean room ..