It's a standard plate packer for that machine with a six inch ring welded to the forward edge of the plate. Fencing guys will have a dedicated one for their machine, excavator guys will some times tack weld a temporary ring to an existing packer for a one off job. We've got rocky soil here as well, the post just pushes them out of the way.I assume this is a type of attachment you can only use with an excavator type vehicle. Perhaps I will rent one when needed. The soil here is crap and there is a lot of rock under it, so an Auger might not even help in the long run.