Review on Ade Advanced Optics Dual Scale Salinity Refractometer (1.0-1.070 S.G.) for Aquariums & Seawater by Vince Preston

Great quality. The LFS store sold the exact same thing for $79! Came with a very nice canvas case, dropper, mini screwdriver, cleaning cloth and instructions. I'm only giving it 4 stars instead of 5 because of the instructions. Nothing tells you exactly how to calibrate it. So here are the steps: 1. Remove the small cap from the pin behind the pointed part and prepare a screwdriver2. Take a few drops of reverse osmosis water, open the top of the slide area and drip onto the slide (tap water works too I've heard but not guaranteed)3. Close the glass cover4. Look into the eyepiece and aim it at the light source, then rotate the eyepiece until you can see clearly5. Turn the screwdriver until the level on the right side of the dial reaches "0" (you zero calibrate the refractometer because reverse osmosis water has ZERO salinity). Boom, you're done! To read this, simply place a few drops of aquarium water on the slide and close the top, then hold it up to a light. That's all! Rinse and wipe after each use. Recalibrate from time to time to maintain accuracy.