Weighing only 1.7 ozs. and collapsing to fit into its own included palm-size stuff sack, the Hydrapak Seeker flexible water container features radio-frequency-welded thermoplastic polyurethane and comes with a no-leak guarantee. The 10"x5.3" container can be frozen or filled with warm water, and its 42 mm cap is compatible with similar-size water filters. Top and side fabric loops allow for attachment to a pack or for hanging the unit from a tree. Price: $18. Contact: Hydrapak; hydrapak.com.