The OP 50 Occipito Anterior Bird Vacuum Cups has the metal suction nipple eccentrically placed at the dome of the cup. If the occiput is anterior, at spines, with some degree of Caput and molding, the Bird anterior cup is suitable.
Made of stainless steel and very less weight and very smooth inner surface. Short traction chain for better control. All rigid cups are equipped with a bottom place mesh. Its function is to distribute the vacuum evenly between the scalp and the suction cup and to prevent the scalp being sucked into the tube connector of the cup.
A separate Steel handle can be hooked into the appropriate link of the chain after the cup is vacuum fixed and used for traction. During traction the index finger rest on the scalp and rim of the cup, and this allows appreciation and not just the Caput the presenting part also detects separation of the cup from the scalp. The suction tube is towards the sinciput.