During the molding operation, a mechanism in the mould unscrews the closure. This action protects the integrity of the thread, therefore ensuring a better thread profile and less distorted walls by the application torque.

During the capping operation, the application torque is better transformed into vertical force that compresses the sealing system (liner or linerless ring) against the bottle neck.

That type of thread has some limitations when it comes to a cap design; for example an interrupted thread cannot be unscrewed. The moulds are also more complex and more expensive to produce.

However there is no restriction concerning the raw materials used to mold the closures.