Want a safe, nature-friendly, and extremely accurate alternative to a mercury basal thermometer? Then look no further than the singular Fairhaven Health Glass Basal Thermometer. It's an ultra-accurate, non-toxic alternative to mercury thermometers that is designed specifically for bbt charting. Containing not a single drop of mercury, the Fairhaven Health Non-Mercury Glass Basal Thermometer is certified accurate - and even comes with a no-break carrying case that acts as a magnifying lens so you can read your basal temperature - and fertility chart - with precision. As you likely know, concerns about mercury have been featured in the news frequently of late. Many states are pulling mercury thermometers from the shelf due to toxicity and related health hazards, particularly for pregnant and TTC women. The Fairhaven Health Glass Basal Thermometer is a highly accurate (laboratory certified) alternative to hazardous mercury thermometers. Containing a safe liquid alloy, our thermometer is completely non-toxic; in the event it breaks, it can simply be cleaned up with warm, soapy water!