Product details:

Add beautiful flower boxes to composite railings with our Lady Windsor Universal Bracket. This modular bracket comes in 4 easy to assemble pieces, and with the handy slotting, makes it easy to accommodate almost any size Trex or composite style railing. Maximum width of railing is 8.5W with a maximum height of 3.75. The bracket to attach a window box to has two holes spread apart at 3.5 on center. You may have to provide your own hardware to install window box to the bracket using both holes. Comes with foam pad to help resist scratching the composite deck.