A wrench comprises a rod, a retainer, a pressing member, and a casing for accommodating the retainer and allowing relative pivotal movement between the casing and the retainer. A GaN wafer which has made by piling GaN films upon a GaAs undersubstrate in vapor phase and eliminating the GaAs undersubstrate bends upward due to the inner stress owing to the misfit of lattice constants between GaN and GaAs. The side bar may be attached to any of a variety of chassis designs and may have a plurality of steps at the doors and at or near the back of the vehicle. The second type is different from the first type. The customer enters the authorization code into the computer to complete the transaction.