An adjustable spanner is provided. The adjustable spanner may comprise a pair of jaw arms, co-operating to move relative to one another, the co-operating jaw arms are each provided at their ends with a jaw, wherein two adjacent jaws constitute a spanner head; a housing for receiving the co-operating jaw arms, the co-operating jaw arms slide longitudinally relative to the housing for setting pre-selected discrete standard fastener sizes, wherein the jaw arms are substantially identical, and are received in the housing being rotated 180° relative to one another about their longitudinal axis.