The One Step OB (Occult Blood) combo test is a simple one step immuno-chromatographic assay for the rapid, detection of human occult blood in feces. The Fecal Occult Blood Test employs a unique combination of monoclonal and polyclonal antibodies to selectively identify occult blood in test samples with a high degree of sensitivity. Elevated levels of human occult blood as low as 10 ng/ml can be detected.