HYGROLID hygrometer The HYGROLID V2 Hygrometer reads Relative Humidity inside mason jars ensuring safe long term storage of Dry Goods. Stainless Steel with food grade material construction. LIFETIME WARRANTY! Hygrolid is the first and best of its kind. Now better than ever! Don't be fooled by imitators! Use with any Wide Mouth Mason/Canning Jar. Prevents molding and overdrying of Dry Goods. Great for curing herbs, for mushrooms, fruit and all Dry Goods.