The ZWO-EFW-Nikon-Ⅱ is a new adapter developed independently by ZWO. It has a thickness of 20mm and is designed to connect Nikon lenses with ZWO's 1.25"/31mm/36mm filter wheels. This adapter has an M42*0.75 thread size and is not suitable for connecting to 2" filter wheels. It is specifically designed for use with ASI cooled cameras with a backfocus of 6.5mm.