Checkline QH2 [QH2DLS] Portable Leeb Hardness Tester for Steel Only w/ Memory for 1,000 Readings Checkline QH2 Portable Leeb Hardness Tester for Steel is used to conduct quick and precise measurements on all types of parts and structures made out of steel, stainless steel and alloy tool steel with immediate conversions to the most common hardness units.