Worm Farming pH + Moisture Meter for Red Wiggler Composting Bins Quickly check the pH and moisture in your worm bin so you can know if your worms are in danger! Easy-to-read gauge alerts you to dangerous conditions with just a glance so that you can instantly react to keep your worms safe. Eliminate the guesswork involved in maintaining your worm bin and experience the peace of mind knowing that you will always know if a problem arises. Nine inch probes reach deep into the worm bedding to get the most accurate readings possible. Perfect for use with the Worm Factory, the Vermihut, and any other worm composing kit. No batteries required.