It didn't work at all. Websites were still managing to upload my information to Facebook - and no, they were not websites or agencies that I gave information to. For example, I wasn't logged in to any service. I had recently performed searches for a specific, one-time product. Thinking I was protected, I logged in to Facebook, and one of the advertisers managed to remarket to me. This is clearly what the description claims it is supposed to prevent. This makes all of the past advertising I dismissed as coincidence a now clear subversion of the purpose of this add-on.