They only appeared in the mission "Chase down metal head beasts", in which Jak had to aim a turret on the Gila Stomper that Sig was driving. After defeating the squad, Jak found the quantum reflector artifact.
These metal heads closely resemble pterosaurs. They have dark green skin, and a large pair of arms, the middle appendage of which extends to a wing, with webbing following all the way down its arm—forming the wings. Under its wings, it has a dispenser for it's missiles. It has two small legs whose usage is unlikely, with a scaly-brown underbelly, and a harness on its neck as if piloting is possible.
In-game, a metal head flyer will just fly around and fire rockets at its target, occasionally screeching. They cannot be evaded in a buggy, and the only way to avoid them is by killing them.
It is recommended to destroy the metal head flyers, as if they are ignored, they will deal incredible damage to the buggy with their rocket launchers. They are very strong and take a considerable amount of time shooting before they go down, therefore a balance between shooting them and the other metal head beasts is advised.