It is adviced to use the Kordon breather bags which allows gas exchange so there is oxygen going into the bag. Heat packs as mentioned above. You can put moss in the bag if you wish, providing you use to breather bags, this will allow the shrimps to cling on during transport. If you don't use breather bags then do not put plant mass in the bag as a media for them to cling on as it will produce CO2 instead of O2 due to having no light instead, you can use some filter floss or pieces of sponges. You can then put the items in a polystyrene box. I would also put some newspaper into the box to stop the bags from rolling around inside as much as possible and to not let the heat packs touch the bags as I believe you can potentially overheat. I would wrap a heat pack in newspaper and place it at the base, then place the bags on top, and then another newspaper/heatpack on top for good measure.