Just three months after Spanish Royal Decree-Law 5/2021 on extraordinary measures to support business solvency in response to the Covid-19 pandemic granted the Spanish Securities & Exchange Commission powers to supervise and evaluate the authorization of crypto asset advertising, it is at this time when the Circular X / 2021 project is submitted to public consultation in order to "develop the rules, principles and criteria to which advertising activity on crypto assets must be subject".This is how the Spanish authorities respond to the massive campaign deployed at the beginning of the year by the Bit2me exchange, which placed 800 posters in crowded points of Madrid promoting investment in Bitcoin, which many considered an aggressive campaign, lacking in regulation and with content that could lead investors to misinformation due to the volatility present in the cryptocurrency market.At Brickken, attentive to the official provisions and regulations that propose modifications in terms of crypto assets, we bring you a summary of the 12 pages that make up the circular.Circular X / 2021 is structured with seven norms classified into three chapters, a final provision and two annexes.The Circular will be subject to comments and observations by public consultation until August 31, 2021, so it is time for believers, as well as crypto assets pressure groups, to establish the points of defense against a regulation that has been described by many, as a strict prohibition and that consequently could discourage competition between entrepreneurs.