All serological pipets are manufactured to the ASTM Standard Specification for Serological Pipets E-934 Bi-directional (positive and negative) graduations are printed in bold easy-to-read ink Premium material barrier plug Color coded stripes and packaging enable quick volume identification Printed indicator arrow for quickly locating negative graduations when using a pipet controller 10mL Wide Tip Serological Pipet for viscous solutions – Wide Tip opening is 4x larger than standard 10mL pipet