The rules, in place since 2015, forbid Internet service providers from creating paid “fast lanes” or giving special treatment to some websites over others.

Many of the websites participating in the so-called “Day of Action” on July 12 are displaying a whirling symbol of a web page loading slowly. Airbnb, for example, is displaying the sign prominently on its homepage as this screenshot shows:

Netflix, meanwhile, is displaying a “Protect Internet Freedom” message at the top of its homepage with a link to a site that instructs users how to contact the FCC:

Other sites with prominent messages include Spotify, Vimeo, and the pornography site PornHub (a banner on its site reads “Slow Porn Sucks”). On Twitter, the site’s public policy group is promoting #NetNeutrality at the top of its trending topics.

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Meanwhile, the technology page of the popular news and discussion site Reddit has an even more dramatic display:

AT&T, a longtime opponent of net neutrality, this week said it would join the day of action, though many regarded its claim as a cynical tactic.

You can see images from what many more sites are doing on an Imgur page compiled by Even Greer, the activist who is leading the Day of Action.

So far, however, it appears some of the Internet’s biggest names—Google and Facebook—have yet to take any prominent steps to join the Day of Action, despite earlier pledges they would do so. In Google’s case, the company has put up a blog post on one of its policy sites describing the case in favor of net neutrality, but not put a message on its homepage.

As for Amazon, which weeks ago announced it would take part in the Day of Action, the retailer has added a “Net Neutrality? Learn More” button to its homepage.

While the largest tech giants are on record in support of the current FCC rules, their size likely means they will be able to negotiate with Internet providers to ensure any changes to net neutrality policy does not affect them.

Despite Wednesday’s broad display of support for net neutrality, and public opinion polls that suggest a majority of consumers—both Democrats and Republicans—are in favor of the policy, the campaign to preserve the rules faces an uphill struggle.

The FCC’s current chairman, Ajit Pai, is an ideologue who has long been adamant in his opposition to the 2015 rules, arguing they amount to undue regulation that hurts business. Since Pai, a Republican, has a majority of votes on the Commission, he is likely to go ahead with his plan to rip up the rules later this summer.