Pmold has the patent for one kind of collapsible core. We design and make the collapsible core by ourselves. Collapsible core is a perfect design for releasing the internal undercut, like the thread inside the cap. Normal design for the cap mold is the unscrewing. However, if we select the collapsible core, it will be cost effective, and mold function will be much stable, most importantly, the cycle time will be much faster.