Those are the same ones I'm using with my MacCat Deluxe. The first 4 came from Dicks then the next set I got with an order from here
They come with a piece of fat, white cord attached to the top. Ditch this for some high-vis reflective cord to make them a little easier to keep track of.
So far these "ground hog" knockoffs hold well in the FL sand and Carolina clay. I haven't tried to pound them into really rocky soil but I figure they'll do OK. When in doubt I'll fall back to my gutter nails.