Dobinsons u-bolt kit. Suited specifically for the thicker Dobinsons leaf springs that offer lift, sold separately. Dobinsons„¢ leaf springs are manufactured from only the highest quality raw materials. We understand the importance of selecting not only the highest quality spring steel, but also the correct grade that will give the longest life under the harshest conditions. Our design engineers ensure that all our leaf springs are designed specifically for each vehicle model, with consideration given to the load and height requirements for each application. Note: Greasable bush kits, greasable pins, and u-bolts are available separately. These do not come with bushings.