This is the refractometer I bought (copied and paste from Reef depot website)
Refractometer w/ Automatic Temperature Compensation
S$59.00 This refractometer, equipped with Automatic Temperature Compensation, is designed for testing the concentration of saltwater and brine. Its triple scale provides a direct reading of the specific gravity and concentration (parts per thousand) of salt in water.
Made of heavy-duty materials for longer lasting use, this item includes a hard carrying case, screwdriver for calibration and dropper for easy place of water sample.
Features
- Easy to use
- Dual scale includes specific gravity and % per thousand
- Automatic temperature compensation
- Easily calibrated
- Adjustable eyepiece
- No batteries required
- Carrying case included
- Includes pipette and calibration screw driver
- Range measurement:0-10%
- Minimum division: 0.10%
- Accuracy: 0.1%