| 摘要 |
A wrench tool is described which has an orifice with a driving end for turning fasteners. The orifice is substantially cylindrical and comprises an array of longitudinal, engaging surfaces positioned therein forming a symmetrical pattern around an imaginary central axis. At least three of the longitudinal engaging surfaces each have at least a small region thereon roughened, and the roughened, internal engaging surfaces form a pattern around the imaginary central axis. And, each roughened region is formed so as to enhance longitudinal friction between the wrench tool and the fasteners. In some preferred embodiments, there is a predetermined total number of longitudinal engaging surfaces, and the total number of longitudinal engaging surfaces is divisible by six using whole numbers.
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