Hematology analyzers or cell counters are the most basic of the laboratory equipment used by hospitals. CBC (Complete Blood Cell Count) machines as they are also called could be either are 3-part differential or 5-part differential. The 3-part analyzer is able to differentiate between 3 types of WBC's (White blood cells) - neutrophils, lymphocytes, and monocytes. A 5-part cell counter can differentiate all WBC types - neutrophils, lymphocytes, basophils, eosinophils, and monocytes. 5-part analyzers are more expensive than 3-part analyzers, but provide more in-depth information about the sample. Specific jobs, such as allergy testing, require 5-part differential analysis. If you are a small hospital or nursing home, a 3-part differential cell counter will take care of most requirements. Most laboratories and medium / large hospitals can use them as back-up machines. It is important not to mix-up reagents and use interchangeably though. Popular brands of hematology analyzers are Sysmex, Horiba, Mindray, Erba, UBM etc.