Let me start by saying I do love these hangers! However straight out of the package they squeak and I will need to find something to properly lubricate them because it’s annoying. 
You also do need to purchase the bolts separately. I just got some galvanized rust resistant lag bolts from the hardware store, along with some washers. And then if you don’t want your rope or chain to have a twist you will also need swing clips. So after buying those two items from other sources you can add an additional 10-15 to the cost of these hangers in order to properly use them. 
Aside from that we love them and they will likely outlast our children.