This large singe-faced HDU sign is supported by two 6 x 6 in Redwood posts on its back side, with a 2 x 8 lateral Redwood beam supporting its bottom. For single-faced signs, back-mounted posts provide more support to the sign than side posts (shorter unsupported width). The rider sign has its "chains" attached to the bottom lateral beam.The "chains" are actual rigid steel links so the bottom sign will not sway in the wind.