Not necessary for a hood to stay on without a jaw, but if you're a bouncy pup maybe get one.
Holes are usually used to push spikes through, but can also be just for visual effect. We sell squishy rubber spikes separately.
If you're adding rubber spikes, it's best not to add a metal trim. If you're not adding rubber spikes it looks better with the metal trim.
The original dog skull pup hood.