The gold standard. The different color labels of Bruco building blocks represent their rarity. Red label, black label, purple label and blue label are all common models, while silver label and gold label are very rare (hidden models). The ratio of silver standard is 2: 27, and the ratio of gold standard is 1: 27, that is, two of the 27 blind boxes of building blocks are hidden models with silver standard, and the production is 1.