This is a two-part test, a collection tube for the blood sample, and a test bar. A sample of the presumed human blood trace is transferred into the tube with transport medium. This mixture is added drop by drop to the test. A positive sample is typically detected within 2-5 minutes. Rapid screening test for the verification of human blood. Test provides a positive or negative result for human blood within 2 minutes. A single red line means the testing liquid is working fine but no human blood has been detected, two red/pink lines mean the test has detected human blood.