The Phase II PHT-975-20 Shore D test block kit consists of 3 color-coded Shore test blocks that range from 10 to 90HA, and Shore durometer results should be within +/-2 Shore durometer points of the stated Shore test block value. It is designed for periodic verification of calibration accuracy and the test block kit is serialized for easy traceability. This Phase II kit can be used with all Shore D durometers.