Abstract: A reversible wrench including a handle portion and a head portion. The head portion has a post compartment with evenly spaced receptacles around it. The post compartment receives a post plate with engagement posts on it. A driving head piece fits at the lower end of the head portion. The driving head includes an integral driving head, slip plate and cylindrical block. The cylindrical block extends upward through the post compartment and is received at the other end by a tab (cover) and is threadably secured with the tab. An arm with a protuberance on it urges the post plate and hence the engagement posts so as to bias the direction which the wrench can be turned.