Product:
Salifert Refract Check Solution (10mL)
35 0/00 solution for refractometers only.

Instructions:
Before each use, shake the bottle, remove and salt scale from the nozzle, and discard the first 3 drops.  Cap the bottle tightly after each use otherwise the value will increase tdue to evaporation.

Note:
Keep out of the reach of children! Only for aquarium hobby use.
The use of protective gloves and eye protection is recommended.
Please read the instructions carefully before using the product. 

Salifert:
Salifert is a Netherlands base company that produces top of the line test kits as well as tank additives and foods for marine and reef aquariums. Salifert is well established and popular with hobbyist for their accurate and affordable test kits.