Yes, it is safe for dogs.
I bought mine at a tack shop but I know there are several places online that sell it. Someone else will probably come up with a site. Or you could just do a search for it. I have even seen it on e-bay.
You will probably have to put it on and leave it for awhile for it to work. I am not that patient and tend to clip, clip, clip.
Welcome to YT!!!!