OS Giken Limited Slip Diferential for the E90/E92/E82 BMW 335i and 135i OS Giken utilized its accumulated racing knowledge and engineering experience to develop its own limited slip differential. Four years of extensive research and development lead to a new and revolutionary LSD design with the capacity to house an unprecedented number of friction plates (up to 28 plates in total) and thus the OS Super Lock LSD was born. The increased number of plates directly has not only dramatically improved our LSD design's locking force and enables it to lock fully and completely. An added benefit to being a fully locking mechanism is that less heat is generated, thus resulting in incredible durability and reliability. As expected from OS Giken, our LSDs are not only made from the highest quality materials, our precise machining, forged gears, and sound engineering makes our LSDs the most durable and reliable race performance LSDs available. In addition, our design allows for the initial torque setting and lock timing to be customized to best fit you vehicle's everchanging set-up and course/road conditions. (Limited to Spec-X LSDs only)