These are made strictly for 750, 1560, and 1590 box drills that do small acreage planting of no more than 1000 acres or less a year. This is a unique product for the box drill industry. What is unique is that though the bushings are not as strong as steel, they are a less expensive alternative in the long run as they do not wear the pin which is the higher cost of the part. You only need to replace the bushings. They also are weather resistant and do not rust. We tested these ourselves on a 42.5′ John Deere air seeder on the back far wing row unit where the wear and impact are the greatest. They lasted 4500 acres. These are self lubricating due to the fine teflon winding of the poly fabric of the bushing design. You can buy these bushings alone and get two sets which is 9000 acres of planting. For those who do small acreage or hobby farming, 9000 acres could be all the acres you will ever do. The pin design and the concept is one that us at Kansas AirSeeder Service has designed ourselves and interested in the feedback for those using it.