We machined these from domestic 6061 billet aluminum and use a theaded bolt to make sure the pin doenst get loose. These are the proper 60mm width and will fit the Nissan springs perfectly. Becasue we start with a billet chunck, the mating faces are flat and allow the spring to sit properly on the blocks and not wiggle or rock. We can also machine these with off-set pins when adding these to our AAL's on the taller applications...this brings the wheel back to the center of the wheel well and also helps with driveshaft plunge. These blocks come with 9.5" long x 9/16 grade 8 zinc-plated ubolts. Kit comes with 2 blocks, 4 ubolts, 8 nuts/washers.