Isothermal bags (also known as Insulated Cooler Bags) offer very good insulation and can keep the products contained inside warm or cold for hours. The sides of these bags can be made in one of two ways:
With three-layer insulation, including a middle layer of 1 mm expanded LDPE. This ensures very strong insulation. The outer layer is usually laminated or metalized film, designed to reflect infra-red waves.
With double-insulated and metalized Polyexpand, which is an economic choice for insulation. This method is thinner than three-ply, but is considerably cheaper.
The bags have rigid plastic handles with snap buttons.