The GoughNuts original rings & sticks contain a patent pending visual indicator system which promote safe play. By implementing the visual indicator (red inner colour) dog owners can clearly see if the GoughNuts’ integrity has been compromised. They followed the basic known concept of “Green means GO / Red means STOP!” when coming up with the idea. Although over time they've expanded their exterior colour selections the concept stayed the same. If you see the red inner layer /core of the toy you should remove it from your dog and contact GOUGHNUTS directly for a replacement.
Please note in order to be safe for play/chewing no toy is created dense enough to be indestructible as that would require the rubber formula to be too hard and could result in damage to your dogs teeth/jaw - even the densest GoughNuts product will pass the "rule of thumb" test most veterinarians reference