No core. It seems the fukuro obi has been sewn to the length of a Nagoya obi (I found this out after purchasing it). It's very light and seems easy to tie. It's a beautiful obi with colors like a watercolor painting of the sea and sky. Unfortunately, it doesn't match the kimonos I own, so I'm putting it up for sale. I would be happy to sell it to someone who understands that it is a used obi that has been stored in a private home. [Size] Total length... Approximately 398 cm, 436 cm when stretched out.