insulated cooler bags,

Insulation: These bags are typically constructed with multiple layers to provide effective insulation, often including high-density fabric, thick pearl cotton, and a reflective liner (like aluminized film) to minimize heat transfer and keep contents cold or warm for extended periods. 

Capacity and Compartments: They come in various sizes and often feature a main zippered compartment for food and beverages, along with additional pockets (e.g., front zipper pockets) for smaller items like keys, napkins, or phone chargers.