The trim handles the lap joints and locks the boards in position to avoid separation on uneven floor. The trim pack includes pre-drilled 3-1/4 inch extensive top rails and corner moldings that connect into the raised bed with provided screws. Our impressions on the Jumbl raised garden bed are that https://holdenumevm.westexwiki.com/702630/not_known_details_about_cedar_for_raised_garden_beds