Kobayashi Toyoko Kimono Gakuin Bias Half-Collar, Collar Core These were found in my home's storage. I don't have much knowledge about collars, so I'm not sure of the details, but one of the collar cores is shorter than the other, so it's likely been used. As for the half-collars, one of them feels thinner than the other two, so it might also be partially used. We would appreciate it if you could purchase them with your understanding and acknowledgment of the above information.