All Agristore USA hydraulic top links come with double piloted check valves. The check valve comes with 3/8" BSP ports and prevents cylinder drift <br> Tractor ball and implement ball are two inches wide <br> The hydraulic top link is double acting with a high quality chrome plated and polished rod and a honed and finished bore <br> All top links are pressure tested, have top quality seals, and come with a 1 year warranty