<p>Use these specially crafted jars with Sourhouse's Goldie (sold separately) to keep your sourdough starter at the ideal temperature. Made of durable borosilicate glass, they're printed with incremental dots to let you know when your starter has doubled – or tripled. Flexible silicone lids prevent contaminants from entering while releasing excess gas. The flat bottom of each jar promotes efficient warmth transfer.</p> <ul> <li>Printed with incremental dots to let you know when starter has doubled – or tripled.</li> <li>Flexible silicone lids keep contaminants out while releasing excess gas.</li> <li>Flat bottoms promote efficient warmth transfer.</li> <li>Made of durable borosilicate glass.</li> <li>Designed to fit inside Sourhouse's Goldie starter warmer (sold separately).</li> </ul>