Silver mylar ballons filled with helium. So far is working as of two weeks ago. I got my balloons from party city and they come on a large clip. Can clip them to tops of tree branches with long ribbon or fishing wire; etc. Any thing else to to heavy. Working great. I also bought a can of helium from the party store as these ballons can be refilled. I have 10 ballons placed in strategics spot in know attack areas.