Cam angle sensor disk for Nissan SR20DET RWD/KA24DE (50 millimeter outer diameter). Use this disk if you have an EMS and need to run a different CAS. New series include this disk and do not require it to be purchased separately. If you are buying your EMS second hand (used), or have a series 1 EMS, you may need to buy this disk if you are having "sync" problems.