The Surface Mount Clamp for Portable Tables by Webcoat is designed for use only with structures that have portable frames. They work on both 2-inch and 2-3/8-inch outside diameter metal frames. These clamps allow you to have peace of mind that your portable table will stay put even if left overnight without supervision. This helps prevent vandalism and theft, ensuring that your table is unable to be carried, knocked over, or otherwise vandalized. It will also keep it stationed during harsh weather that may try to blow it away. The clamps do not include bolts when purchased. It is recommended that you use heavy lag bolts for added protection. Your installer may choose to use their own personal preference when installing these surface mount clamps. Each order comes with two clamps to ensure that your picnic and seating areas remain safe and intact. Be advised that these clamps are only for use with portable style tables and benches.