You want something that is too big for him to chew once and swallow. Also, something he can actually eat. Bones that are too hard damage the teeth. Wolves have big tough teeth, dogs don't. Depending on how big he is, you could start with chicken backs. That is, the spine, neck, and pelvis. Chickens are small creatures and are butchered usually at eight weeks so the bones are soft. As he gets bigger you could move to ox tail.
A round bone, being shaped like a ring, can get caught around the lower jaw, but you could cut it in half. Just remember, small enough for the dog, but too big to be swallowed whole.
Bones are a somewhat fraught topic - some think them essential, others consider them too dangerous. As a general rule:
Raw bones only - never feed cooked bones
Soft bones only - avoid weight bearing leg bones etc, that are hard enough to crack or break a tooth
Give bones big enough not to be a choking hazard, and remove the pieces when they have been chewed down
Watch the additional calcium if the bones are actually consumed, rather than simply chewed on, especially for a puppy
Bones can be very high value for a dog - be aware of potential resource guarding!
Chicken backs, lamb spines, lamb or pork ribs are all possible - remove excess fat first.