Small metal jar jars are so-called pop-top cans, whose lids and jars are produced separately and assembled together at the end. The advantages of this metal can are obvious, its tightness is very good, and it can resist high internal pressure. There are two materials for making cans: aluminum and tinplate. Due to the high recycling value of aluminum, aluminum cans have begun to be used in large quantities for environmental protection reasons.
The strong rival of aluminum in the packaging industry comes from PET materials. PET material can be made into fancy shapes by injection moulding, but aluminum is more difficult. However, the price difference between the two is huge. PET is affected by oil prices, while aluminum can be recycled to reduce material costs.