Tap My Trees Maple Sugaring Glass 9-1/2 In. HydrometerMaple syrup glass hydrometer with Baume scale (25 40) and Brix scale (45 75). For use with hydrometer test cup. Measures the density of maple syrup at a specific temperature. Professional grade, used to determine when to stop boiling. 9 1 2 inches. Instructions included. Calibrated specifically for maple syrup, not to be used for other purposes.