Field kit is primarily used for staining standard thin and thick blood smears, i.e. dense drops for the purpose of diagnosing blood parasites (such as Plasmodium which causes malaria). Because the amount of parasites in blood samples tends to be low and almost unobservable in standard blood smear, the preparation of thick blood smear enables 15-20 times higher sensitivity of the diagnostic method. Thick blood smears are not fixed; they are treated with hypotonic dye solution after drying on air. During that procedure white blood cells (leukocytes) are preserved and stained, while red blood cells (erythrocytes) are hemolyzed which in turn makes viewing of other present structures in blood under microscope easier. Thin blood smear staining should always be conducted at the same time as thick blood smear staining because the control of such smear enables parasite differentiation. Besides this, Field kit can also be used as a Romanowsky dye for rapid routine staining in hematology; it can be used for staining standard blood smears and bone marrow, but also for staining Helicobacter pylori in stomach histology samples. Each part of the Field kit is stabilized separately and prepared according to the highest standards.