If a radon vent pipe passes through a fire rated wall, Nelson fire barriers are required. Garages have a fire rated wall where they connect to the house. If the ceiling is drywall also a fire barrier is used to suppress fire from entering the attic. Since PVC pipe will burn and melt rather quickly, fire collars are necessary to stop the spread of fire into the home or attic. When heated the putty in the collar expands to fill the hole.
They are a building code requirement.
Some collars require smoke sealant caulking, these do not. Simply wrap around the pipe and attach to the wall with 4 screws.