A frozen screw or bolt can present a tough problem. The professional way to handle this is to use an impact driver. The Large Impact Driver comes with 13 separate bits: 4 slot, 4 phillips and 4 hex (4, 5, 6 & 8mm) plus a 3/8″ socket drive. Simply place the correct bit in the impact handle, then strike the end of the heavy steel handle to crack the screw loose. The rotary force is automatic.Our companion Small Driver is specifically for small scale fasteners (slot or phillips screws and hex head bolts 3/16″, 1/4″ & 5/16″ in diameter. When you need one of these tools, you really need it. Reversible, of course. We strongly recommend both sets for a full range of capacity.