A small frozen ice pack we ship with your yeast and other cold products to maintain cold temperatures during transit. These are highly recommended to prevent yeast from rupturing in high heats. Even with ice packs, transit in summer months can be too hot for ice packs to effectively cool yeast, or they will melt too quickly. As such we cannot guarantee yeast health on delivery. If ordering during summer months, dry yeast is recommended. Brand of ice pack may vary.