Why would anyone travel with up to 4 pounds of dry ice???
http://www.alaskaair.com/as/www2/help/faqs/CheckedBaggage.asp
"Dry Ice
Dry ice may be placed in carry-on and checked baggage subject to the following limitations: In all cases, the packaging must allow for the release of carbon dioxide gas. For carry-on baggage, each person may carry up to 4 pounds of dry ice. In checked baggage, the limit is 5 pounds per package. The package must be marked with the net weight of the dry ice or the statement that the net weight of dry ice is 5 pounds or less. The name of the contents being cooled, along with the words "Dry Ice" or "Carbon Dioxide, Solid" must be on the outside of the package."
http://www.alaskaair.com/as/www2/help/faqs/CheckedBaggage.asp
"Dry Ice
Dry ice may be placed in carry-on and checked baggage subject to the following limitations: In all cases, the packaging must allow for the release of carbon dioxide gas. For carry-on baggage, each person may carry up to 4 pounds of dry ice. In checked baggage, the limit is 5 pounds per package. The package must be marked with the net weight of the dry ice or the statement that the net weight of dry ice is 5 pounds or less. The name of the contents being cooled, along with the words "Dry Ice" or "Carbon Dioxide, Solid" must be on the outside of the package."

