AEM Cas Trigger Disk 54mm OD Nissan Pulsar GTIRAEM CAS Trigger Disk 54mm OD. NISSAN: Pulsar GTiR AEM cam angle sensor discs are for use with AEM programmable engine management systems They are a direct replacement for the factory crank angle sensor disc in your Nissan. Before purchasing, be sure that the center of the AEM CAS disc looks exactly like the stock disc in your distributor. Be sure to match the hubs of your disc to the AEM disc before ordering.