Accu-Chek Instant Blood Sugar Control 1 & 2 Solution are specifically designed to work with your meter and test strips to confirm the accuracy of your results. The control solution contains a known amount of glucose. Simply use it instead of blood on a test strip. If the result matches the expected glucose level, your meter and test strips are working properly. You can run a control test with control solution any time when you open a new test strip box, if the test strip container has been left open, if you think the test strips might be damaged, if you want to check the meter and test strips, if the test strips were stored in extreme temperatures, humidity or both, you dropped the meter.