The 2 classes are Class A and Class B. Course A pipettes are created to exact tolerances, or "mistake limitations". Course B are permitted twice the mistake boundaries of Class A. The class specification or serial range of Course B will not be marked. Together with regular types of pipettes, https://types-of-pipettes-used-in45555.thenerdsblog.com/34979748/the-ultimate-guide-to-types-of-pipettes-pdf