Patent ID: 7424839

Claim:
A wrench comprising: a body having a thickness, a proximal end, a distal end, two arms separately formed on the distal end and forming a mounting recess between the two arms, each arm having an outer surface, a free end, and a hole defined through the arm near the free end, wherein the two holes in the two arms face each other, wherein the hole defined in each arm of the body further comprises an inner thread formed near the outer surface of the corresponding arm, and a handle mounted on the proximal end of the body; a head pivotally mounted inside the mounting recess in the body and having a thickness, an outer surface, a driving hole defined through the head, and two pivotal holes defined in the outer surface and respectively corresponding to the holes in the arm of the body; and two pivotal devices respectively mounted between the arms and the head to hold the head in the mounting recess, and each pivotal device having a holder mounted inside a corresponding one of the holes and having an outer threaded portion screwed with the inner thread in the corresponding hole, a pivotal rod mounted inside the corresponding hole, being held by the holder and having an enlarged end received inside a corresponding pivotal hole in the head, a spring mounted around the pivotal rod and abutting the enlarged end and the holder, and a resilient tab mounted on a corresponding arm and having a proximal end mounted on the corresponding arm, and a distal end mounted with the holder.