OPTIONAL ice pack and Insulated shipping liner. While enzymes are heat sensitive (They should stay below 85 degrees F for long periods of time) we have had very few issues with heat damage in transit. If you would like your enzymes shipped with ice in an insulated liner this is available. Please note that the reusable ice pack is good for approx 24 hours and temperatures will play a role in how long the ice will last. Smaller packages will be an envelope with a shipping liner, larger packages will be in a box with liner. Most of our packages ship without ice and are fine. We are shipping from NE Ohio.