The founder of TOMS Shoes, Blake Mycoskie, decided in November 2018 to try to do something about gun control in the U.S. On Monday, Mycoskie was publicly joined by three CEO peers, who co-signed a letter to members of Congress, calling for them to pass an act calling for background checks.

Levi Strauss & Co.’s Chip Bergh, RXR Realty’s Scott Rechler and Dick’s Sporting Goods’ Edward Stack have each spoken out about gun control before, but joining their voices together is an important moment in CEO activism. Each has determined that they can and should use their profile and influence to guide the country in ways they believe right.

Mycoskie reveals that about 12% of TOMS customers will cease to buy his shoes as a result of his gun activism, but that other customers will be more loyal and new customers will be attracted to the brand. Each CEO had to make their own decision about the net effect of activism on their sales and their employee retention, but Mycoskie and the other CEOs are now running test cases of how CEO activism impacts brand.

At the same time, because these CEOs have joined together, they have provided air cover for other CEOs who want also speak out in support of this movement, but are concerned about the impact on their brand. Mycoskie, Bergh and Stack in particular, being more well-known, and first movers, are the ones that will be named CEOs in any media coverage, significantly reducing the risk to the next group of CEOs who join.

Whether the CEOs’ letter will have any impact on the House vote on Wednesday is questionable. But certainly they have shown their stakeholders who they are as CEOs.