(Reverse Thread, locks on and backs out broken studs. Extract a wide variety of screws, easy to use. Sizes: #1) 1/8"-1/4", #2) 1/4"- 5/16", #3) 5/16"-7/16" #4) 7/16"-9/16" #5) 9/16"-3/4", #6) 3/4"-7/8".