Abstract: An adaptor comprises a housing, a body, a pawl, and a switch member. The housing includes an end for engaging with a socket. The body includes a first end to be engaged in a box end of a wrench and a second end received in a compartment defined in the other end of the housing. A pawl is pivotally mounted in a transverse groove in the body and includes two toothed sides. A switch member includes a first end for manual operation and a second end engaged with the pawl. The switch member is pivotable between two positions corresponding to two opposite ratcheting directions to selectively urge an associated one of the toothed sides of the pawl to engage with the toothed inner periphery of the housing.