Refractometer (Brix Scale)
This is a great tool to more conveniently measure your specific gravity when using your all grain brewing system. When using a hydrometer, you need to get a trial jar sample of wort from your brew when it is near boiling and then wait for the wort to cool before getting a reading. With the refractometer you only need to take a small sample using a spoon or pipette straight from the wort and only wait a few seconds before dropping a very small sample on to your refractometer.
This refractometer measures in Brix, but comes with a conversion chart to SG for your convenience.