Rebuilding Caliper question

When I took the old dust boot off I noticed there is some kind of grease or something that adheres that part of the boot to the body of the caliper. And then it appears the wire clip goes on top of the boot to hold the boot in. If there is something that adheres it what is the name of that product? I think it is as simple as something there to keep dust out. But what are they using?

One more thing - these are the original boots on these calipers