The IceCap SPT03 Digital Salinity & Temperature Pocket Tester replaces a mechanical refractometer with an electronic conductivity-based reading, giving accurate salinity and temperature results in seconds on a backlit LCD screen — no calibration fluid mess, no squinting through a lens. Measures: salinity and temperature Method: electric conductivity for fast, reliable readings Display: backlit LCD, easy to read in low light Calibration: push-button, single step Build: compact, water-resistant, portable Refractometers require regular calibration fluid checks and can drift or give inconsistent readings if the optical surface isn't clean — an electronic conductivity meter like this sidesteps both issues with a simple push-button calibration.Best for: reef and marine aquarium salinity monitoring, both natural and artificial seawater.