The BD BBL™ Acid fast Bacilli (AFB) QC Slides are conventional 1 x 3 in microscope slides imprinted with two circles. One circle is an acid-fast positive control with Staphylococcus aureus and Bacillus subtilis plus inactivated Mycobacterium tuberculosis H37Ra. The other circle is a negative control with an unstained mixture of non-acid-fast cocci (Staphylococcus aureus) and bacilli (Bacillus subtilis). AFB Slides, individually wrapped, sufficient for 50 tests.