Please see our instructions on how to prepare a dry shipper. Depending on the condition of a dry shipper and how well a it has been prepared, samples could potentially be stored in a Dewar for several day to a week (without dropping to an unsafe temperature). This is especially helpful if your shipment is traveling a long distance; you have not selected expedited shipping or over holidays where a shipment might arrive with no one available to receive it. Earn a merit badge on charging a dry shipper at: Cryo-EM Merit Badge: Cryogenic Sample Shipping.