Excellent tool.  It does slip a little if you are not careful, but makes it a breeze to remove the bolt.  I used a breaker bar in the hole on the tab and wedged it against the ground.  I only had a 3 inch 1/2" drive extention which gave me little room to work with.  Figured out I could take a jack and use the jack to push the wrench up while using a 2x4 to hold wratchet in place.