Patent ID: 8056448

Claim:
In a multi-size wrench comprising at least one head with an engaging hole for engaging with fasteners and a handle portion, an inner surface of the engaging hole of the head being formed by six arc-shaped engaging concaves and six arc-shaped connecting convexes which are alternatively connected to each other in such a manner that between each two neighboring engaging concaves is connected a connecting convexes such that the engaging hole of the wrench is applicable to both a Metric hexagonal fastener and a correspondingly sized English hexagonal fastener, the improvement comprising: each of the engaging concaves includes a first engaging end, a second engaging end and a middle engaging point, and each of the connecting convexes also includes a first connecting end, a second connecting end and a middle connecting point, an angle between the first and second engaging ends of the engaging concaves with respect to a center of the engaging hole is 49Ëœ51 degrees, an angle between the first connecting end and the middle connecting point of the engaging convexes with respect to the center of the engaging hole is 4Ëœ6 degrees, so that the engaging hole of the wrench is also applicable to a correspondingly sized torx fastener.