Every material is bulletproof if you lay it on thick enough, and no material is bulletproof if you have a big enough bullet. What materials are used to make bulletproof products in particular are bound by what you can carry and what modern weaponry you can expect in the field.

For this purpose, we can look at three categories of materials:

High-density materials
High-tensile fibers
Composite ceramics

Here introduce some material that we used for bulletproof products.

Aramid

Aramid is a truly wonderful material. It is simultaneously ‘space-age’ and works on the oldest ballistic principle imaginable.

It works like chainmail, but on a molecular level. Strings of aramid are pressed together to make sheets like in the linen cloth originally. But, unlike linen, aramid has a much stronger connection to itself and can pull the entire string every time one part is pressed.

This quality makes it ideal as soft armor, as it is flexible on slow touches and only becomes firm once it encounters something really fast. 

And we normally use it for NIJ IIIA ballistic helmet, NIJ IIIA ballistic vest. 

Aluminum Oxide

Aluminum Oxide is a very obvious choice when it comes to ballistic materials, and is still one of the most common types of armor, mainly because of its price and availability.

Its ballistic properties have everything to do with the molecular structure inside. When looked at as a whole, it seems like rows of interchangeable zig-zags that press onto each other. This makes the material both very firm, but also quite flexible.

When under fire, the pattern bends and forces the rest to squeeze the bullet, slowing it down and stopping it in its tracks.

This does make Al2O3 armor slightly heavier than the rest, but not as much that it is unbearable.

We normally use it to make ballistic plate and ballistic shield.

UHMWPE

This is one of the best materials to come out in the last 100 years. Polyethylene is a plastic that is quite easy to manufacture and it is mostly air. But, when it is made in its ‘’ultra-high-molecular-weight’’ form, or as UHMWPE, it becomes very resistant to bullets.

The extremely long chains of polyethylene create the same effect as all fibers. But, the strong hydrogen bonds make its tensile strength unmatched by anything else. This is why a very light hard plate made from UHMWPE can stop even rifle rounds.

It can make NIJ IIIA ballistic vest, ballistic plate, ballistic shield, ballistic helmet and so on.