The theory of over Molding Jar / Bi-injection Jar : The Bi-injection is a kind of novel skill to injection two different materials / colors into a mold at separate injection locations, which are controlled independently by two different injection units. The usage of Bi-injection: By the skill of bi-injection, perfect combination with different colors of outer and inner layer to present product's uniqueness. Product specification on Bi-injection: Please find detailed information by click the link of PP bi-injection cream jar.