Here's What It Means When Steak Is USDA Certified Tender - Tasting Table
Briefly

In the early 2010s, the USDA realized that their quality grading programs didn’t measure tenderness, one of the most important characteristics of a steak cut.
The tender certification ensures that beef must achieve a WBSF score of 4.4 kg or an SSF score of 20.0 kg, guaranteeing excellent tenderness.
Meat that holds a tender label offers excellent tenderness regardless of whether it carries a prime, choice, or select label, assuring consumers of quality.
To receive the 'very tender' certification, meat must exceed the basic tender requirements, indicating an even higher level of tenderness for discerning consumers.
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