When you order one liquid yeast from us we ship it with one 4 oz. ice pack. In the summer months this may not be adequate to keep the yeast cool. If you order this option when ordering one liquid yeast, we will upgrade the 4 oz. pack to an 8 oz. size. If you order this option without ordering liquid yeast, we will ship you a 4 oz. ice pack. These are cold packs that are filled with a non toxic gel and frozen before shipped. One 8 oz. pack will keep yeast cool for up to 6 days in transit. We recommend one of these for every 4- 6 yeasts, especially in the hotter months. Limit one of these smaller 4 oz. packs per order. If you need additional ice packs please order the 8 oz. size which has no order limit. We include one free gel ice pack with every order of liquid yeast. Purchase additional packs if needed. These ice packs can be reused dozens of times; simply re-freeze and they are ready for an ice chest or other application.