Our Marrow bones are filled "naturally" with marrow. Dogs love chewing these to get the marrow out. These, like the cut centers - when the marrow is gone, you can back-fill these with Peanut Butter or Yogurt and give back to your dog for more hours of enjoyment. We do offer (2) sizes. Reg size Marrow: Good for dogs up to: #35 $ 6.00 Large Marrow bones: Good for dogs over #35. any breed. $ 8.00