They are test strips used with the Accu-Chek Guide blood glucose monitoring system to measure blood glucose levels. The Accu-Chek Guide system is designed for people with diabetes who need to monitor their blood sugar regularly. The test strips use advanced technology to provide accurate readings and require a small blood sample size. The Accu-Chek Guide 50 Strips are sold in packages of 50 and are available at most pharmacies and medical supply stores.