I searched for swing arm spools at Motosport with products filtered for a Kawasaki Ninja 250. From the products listed for the Ninja 250, I initially ordered the Yoshimura Universal Race Stand Stopper. However, it did not fit my bike - the thread pitch on the 10mm bolts was wrong. Fortunately, the good people at Motorsport took responsibilty for the incorrect listing of the product, and I got these Yoshimura spools instead. However, I was still disappointed. On the right side swing arm, the product fit perfectly. However, on the left, it was difficult to install. I had to work the bolt in and out many times, and small pieces of metal sere shaved off. It's odd because the bolts look identical. I've read online about others with the same problem.