Fig. 1From: Perspectives on rapid fentanyl test strips as a harm reduction practice among young adults who use drugs: a qualitative studyFentanyl rapid test strip results label. This is the key that was placed on each of the FTS packages to assist with interpretation of the test results. This key shows that a strip with one red line indicates a positive test and a strip with two red lines indicates that the test is negative, but that the participant should still use cautionBack to article page