Bob does make foam core Cheyenne limbs with carbon backing if you want them, but in the lower weights Bob says you don't lose much in speed without the carbon and the carbon limbs in low weights are not as smooth as the ones with only fiberglass. Therefore, Bob only recommends the foam core Cheyenne limbs in higher weights, like 60 or 65 pounds and above. That leaves me out! In the Shawnee Dakota limbs he recommends the foam core carbon limbs even in the weights as low as the 40's because the narrower limbs behave differently with the carbon laminations as compared to the wider Cheyenne limbs. He is building me some of the Dakota limbs in the low 50's and is using the foam/carbon combination. Maybe someone could ask Bob to post his suggestions here in case I am incorrect in some respect, but I am telling you what I remember him saying to me a couple of months ago when I was placing my limb order with him.