Just want to thank you for helping me when the swallow made their nest in my vent pipe.As you recall the nest was in the vent about 4 feet and I could not get it out. I want to thank you again for sending your man out and taking the vent pipe apart and blowing the nest out of the pipe. That little cover you put over the vent sure works good, the little swallow came back about 5 times and tried to get in again and then went some where else. I looked a couple times in the winter and there was no frost buildup on it, thanks again.