Hardness tests have always been important to conclude on specific mechanical properties of materials in a fast and economic manner, i.e. in a (quasi) non destructive test. This paper has its focus on the most recent test method, the dynamic rebound hardness test method after D. Leeb. The EQUOTIP, Leeb's original instrument, is fully discussed and newest improvements are presented. So far, PROCEQ SA, Swiss manufacturer of the instruments, maintained and protected the constancy of the L-Value over the last 30 years. Recent round robin results show the way, where standardization work can be improved to hold the high level of reliability of the measuring base, the L-Value.
