Type A Durometer (ASKER A type), conforming to JIS K 6253-3 is the most popular type of durometer for measuring rubber hardness.
However, verification is recommended because a significant difference is estimated to be the largest when a durometer indicates measurement values from 10 to 90 points.
For hard specimens for which Type A Durometer readings indicate more than 90 points, measurements should be undertaken using the Type D Durometer (ASKER D type). However, for soft specimens with measurements of less than 20 points, the ASKER C type or Type E Durometer (ASKER E type) should be used. The most important consideration in using durometers is to select the correct type for purposes of measurement according to the specimen.