The Zaklee Bolt Kit for the Nissan Skyline RB20 & RB25 engines is carefully engineered to allow mounting the Zaklee clear cam gear covers without cracking or otherwise stressing the part. Just drive the bolts down until the shoulder bottoms out on the mounting plate, and you are done! The custom-wound springs provided take up the gap between the head of the shoulder bolt and the clear cam gear cover, ensuring that the cover stays firmly in contact with your engine.