I hate those things... I tried them, and getting them in straight, in the hard Texas Clay is more work than I want, and we recycle our signs for the clients, and if you want to reclaim them, bring a good jack and a small chain to pull them out of the ground. I plant our signs about 16" for a 4x4 or 4x8 on 8' poles. The signs don't look good after a while, as they tend to wear away the wood on the post, where it meets the metal, and then they wobble and lean. A little exercise is good for me anyway. I'll dig the holes before I go that cheap route again... and good customer service will sell many more jobs. Ciao!
"Be the job big or small, do it right or not at all!"