I travel every week and take a guitar with me. I use the D'Addario paks in the cases for all three of my guitars, but when I take one to the airport, I remove the paks. Reason: the TSA often wants to test the liquid in the paks and I fear they will confiscate them. So I replace them with a simple sponge system.
Richard Brune 1980 Concert Model Spruce Brazilian Rosewood
Richard Brune 1993 Concert Model Spruce Cypress #568
Kenneth Hill 2002 Hauser Model Spruce Maple #999