Light passing through a liquid is refracted or bent proportionally to the density of the liquid, the more dense the liquid the more slowly the light passes through. An optical refractometer determines specific gravity by measuring the refraction (bending) of light passing through the sample of electrolyte as compared with the refraction of a ray passing through pure water. Water has a specific gravity of 1.0 and the electrolyte in a fully charged battery has a specific gravity of 1.265, that is, the electrolyte is 1.265 times more dense than water.

Perfectly suited to measuring battery condition in difficult locations, as only a drop of electrolyte is required. When you are done simply rinse with distilled water and store in carrying case. Safer, more convenient, easier to read, store and transport, more robust than fragile hydrometers.

Also includes scales for Antifreeze, both Propylene and Ethylene Glycol.

Compact 1.6" dia. x 6" long  Specific gravity range 1.10-1.30 Accuracy +/- 0.01 weight 8 oz..

Comes with: Carrying Case, Plastic Transfer Pipet , Instruction manual and Free Thermometer