A Zeal wet and dry bulb hygrometer is an analog instrument used to measure relative humidity by using two thermometers—one wet-bulb and one dry-bulb. Key details include its molded plastic case, analog operation (no batteries needed), a temperature range of about -8°Cnegative 8 degrees cap C−8°to +50°Cpositive 50 degrees cap C+50°(20°F20 degrees cap F20°to 120°F120 degrees cap F120°), and being supplied with hygrometric tables to determine humidity from the temperature difference. For example, Essae's product line shows these differences in accuracy across different applications: High-precision laboratory balance: The AX series uses Electromagnetic Force Restoration (EMFR) technology to achieve high sensitivity. For a 620-gram capacity model, the accuracy (readability) is 0.001 grams (1 milligram). Jewelry precision balance: Some JX series models for weighing precious metals offer a readability of 0.005 grams (5 milligrams) with a capacity of 320 grams. Retail counter scale: The DS-252 counter scale, which is used for weighing food items, has a lower accuracy requirement. It offers a capacity of 15 kg with an accuracy of 2 grams. Industrial platform weighing scale: For heavy-duty industrial tasks, the DS-215SS model is available with a capacity of 100 kg and an accuracy of 10 grams.