Temperature shipping packs

[ChrisQ0904]

I was wondering which shipping cool/heat packs were the best? I see that a lot of people are using 30/40hr unitheat packs for the winter but I cant seem to find any information about cool packs. What material/brand is best when it comes to cool packs?

Mods: I didnt know which section to post this in, if this is the wrong section please move or close and PM me the proper section to post this question.

 

[Scorpius]

Most places I see freeze a tube of water and use that as their cool pack.