Kryptonite Stronghold (above ground) item #330202. It uses three 5/8 inch diameter steel concrete anchor bolts beneath a cover secured by the padlock. It is a very good design. I paid $60 about 4 years ago for it. The "Kryptonite New York Fagettaboutit" lock and chain (was $90) secure the bike to the stronghold. Very secure. Don't get a cheaper lock (some can be foiled quickly by a cold gas "freeze" spray and a sharp strike with a hammer).
--Tom
