Break away hardware is typically used with U-channel and square post installations.  The nut is installed with the hex shaped section away from the sign post which (in theory) breaks free when properly tightened. This leaves a tapered nut and makes the sign a bit more difficult to steal.  This works well with square posts, but not so much with u-channel posts.  When installed on U-channel posts we recommend to either use back plates to reinforce the sign, or using pliers to break the hex section free once the sign is up tight against the post.  Otherwise, the sign panel will be pulled into the channel of the post deforming it before the hex section of the nut breaks free.