THESE KITS, CONSISTING OF AN EYE BOLT, 2 PRESSURE PLATES AND A SPRING, CAN BE ORDERED TO CONVERT ANY BLOCK INTO A SPRING-LOADED PIVOT BLOCK. THE STAINLESS STEEL SPRINGS ALLOW THE INSTALLATION OF STANDARD AND PIVOTING BLOCKS POSITIONED VERTICALLY ON THE DECK. PROPER LINE OPERATION IS ENSURED AND DAMAGE TO THE DECK IS AVOIDED