The SP-10 Male Fertility Rapid Test Cassette detects Acrosomal Protein SP-10 found on sperms. Since, SP-10 is a protein specific to male germ cells and cannot be found in other cells. This test is very specific for sperms and is now being used for estimating sperm concentration in semen as an aid in determining causes of infertility. The SP-10 Male Fertility Rapid Test detects SP-10 gives a normal result, when sperm concentration is above 15 million/mL in semen – a level internationally accepted as the minimum level of sperms for normal fertility.Because low sperm count is a leading cause of male infertility, an important first step in determining the cause of infertility is to test the sperm count.