The advantage of ceramic armor is that it is not only lighter than metals, but much harder as well, which enables it to deform tungsten core penetrators and resist ammunition at a high velocity.
[9] Most metal ballistic plates are made primarily of steel or titanium, although aluminum and various alloys also exist.
[10] In addition, metal armour has the possibility of deflecting bullets, where they may end up in a limb, friendly personnel, bystanders or property.
Munitions above 3100 fps have been known to penetrate commercial armour steel plates sold under NIJ Level III, most notably the 5.56×45mm M193 round.
[12] Multi-layered sheets/plates of ultra-high-molecular-weight polyethylene (UHMWPE) can provide an added ballistic enhancement equal to or even greater than metal plates with less weight.
[13] UHMWPE however, does have weaknesses, most notably its vastly inferior heat and flame resistance due to being a thermoplastic with a low melting point (130 °C (266 °F)).