Abstract: An angularly adjustable coupling includes two coupling members pivotally mounted to each other about a pivot axis. One coupling member includes a locking rib of circular configuration coaxial with the pivot axis, and the other coupling member includes a pair of pivotal arms having locking surfaces normally engageable with the locking rib to lock the two coupling members against pivotal movement, but manually moveable to release the locking rib and to permit one coupling member to be pivoted with respect to the other to any desired angular position.