This is the ‘window box’ planter, not the ‘railing planter’. They don’t include photos that make the distinction obvious, but these two planters come with different brackets. Turns out I needed the railing planter. I contacted veradek and they’ll ‘sell’ the other bracket for $45 each.  More helpful photos and description would have helped. It’s not worth rerunning them, so on the ground they go. 
Otherwise, same great quality and would have loved to give them 5 stars.