I don't know the material. The fabric is dark navy blue. There is no obi core. There is a pattern on the otaiko part in photo 1 and on the chest in photo 2. Width: 30cm, Length: about 3 meters. I don't know much about obis, so I can't explain it. Please understand that this is a used item based on the photos only. It's beautiful, but it has been used several times. For those who will recycle it.