The ZWO M54 sensor tilt plate is used as a replacement for the tilt plate supplied on the ASI2600 series cameras (and similar). The tilt plate that comes with the camera has a 42mm opening. If you need to connect to an M54 filter drawer or similar component, you will need to replace the sensor tilt plate.

Note: this part is different to the two-part M54 Tilter (SKU: ZWO-M54-Tilter). The sensor tilt plate has only one part and normally sits at the front of the camera, or may be moved to the OAG-L.