It supposed to stop squealing and called anti- squeal grease sometimes although I think its just black antiseize. I tried it on the sliders in the past and it gums up so I wouldn't anymore. It is not a smooth grease and looks like it has metal in it.
You can buy a tube of synthetic caliper pin/brake squeal grease for a couple bucks. Its clear blue and made by versa chem. It should be enough for at least 10 brake jobs. I like it