The MD-Bio Fentanyl & Xylazine Test Strip Kit is the easiest, fastest and most accurate way to detect trace amounts of fentanyl and xylazine (also known as 'tranq') in packaging, pills, on surfaces and more. Once the tests have been run, result interpretation is simple! One or two pink lines will appear on the test strips to indicate whether fentanyl or xylazine has been detected. One line indicates a positive detection for the presence of the substance. Two lines indicate a negative detection and that no substance has been detected.