The YETI insulated cool bags use advanced Coldcell Insulation technology and a super tough DryHide Shell to keep food and drinks cold for extended periods. The closed-cell foam insulation is more efficient than traditional foam and works to slow down the transfer of heat to maintain cold temperatures inside. The DryHide™ Shell is resistant to punctures, abrasions, and UV rays, ensuring your cool bag stays durable in the harshest conditions. Alongside this, the HydroLok zipper is leakproof and airtight, preventing warm air from entering and cold air from escaping. This combination of a leakproof design, superior insulation, and easy portability makes our YETI cool bags ideal for whatever activity you need them for.