The use of top mounting clamps is generally easier when flush mounting to a roof. Always use top mounting clamps when flush mounting to standoffs. If using bottom mounting clamps with L-feet, follow the installation manual carefully to make sure footing slots are accessible during final installation. In order to determine which set of clips is compatible with your module(s), please refer to the PDF Sizing Chart below. If you have any questions about UniRac SolarMount, please call us.