Refractometers are used to measure the Brix levels of fruits & plant tissue to determine when crops are ready for harvest, as well as measure the effectiveness of a fertilization program and estimate plant health.Organic agricultural consultants have reported that plants with higher than normal Brix levels are more resistant to rasping insect pests.This model includes automatic temperature compensation & measures from 0- 32 Brix. Easy to use & understand. A very useful tool.