This plate was 10oz lighter than the Alumina plate, but that seem to cost it better multi hit capability. If you want a cheap and light level IV, this will fit the cake. Only is single curve, and NIJ04 Compliant.

That's a good observation. They're both brittle materials, but alumina is typically tougher than silicon carbide.

Roughly, and on average [1], armor-grade SiC has a fracture toughness of 2.5 (KIC -- MPa * m^1/2), and armor-grade (99%+) alumina has a fracture toughness of roughly 3.5 to 4. If you were wondering, the zirconia ceramic they use in cutlery, like those cheap chef's knives, is around 6-7. Tungsten carbide, of AP bullet core fame, is around 12-15. The hardest and most brittle tool steels are around 20, and tough grades of steel, like certain maraging steel alloys, can easily reach around 150 MPa * m^1/2.  I think that there are experimental steel alloys at around 400.

So the gap between 2.5 and 3.5 might not seem like much -- but it is a roughly 40% difference in relative terms, and it sure looks like it makes a difference!  Between this video and a few others, it's really starting to seem that alumina plates have significantly better multi-hit performance. Makes me wonder about zirconia for armor purposes.

[1] - The toughness of ceramic materials is hugely influenced by how they were processed, the quality of the raw materials involved, and their porosity.

To me, it seems like a great value, at $233/set shipped.

https://www.aliexpress.com/item/Two-Pieces-Set-Alumina-PE-NIJ-IV-Bulletproof-Panel-Al2o3-NIJ-4-Stand-Alone-Ballistic-Panel/1511609999.html?spm=a2g0s.13010208.99999999.259.2ecf3c00wkStHf

But its Chinese... and that really seems to concern many people.

Also single curve.

Can't decide if triple curve, steel, level III are better, or these chinese, single curve lighterweight lvl IV.

Also the RMA plates seem pretty popular right now

https://rmadefense.com/product/level-iv-hard-armor-plate-model-1155/

Any plans to test the VISM plates?

Their III+ or IV? They sure do scream Chinese with that edge on them, but they say assembled in the US. HMM

Some people, who get really butthurt if you mention them on ARFCom, import Chinese plates and put the liner on them (or a similar trivial assembly task), so they can claim assembled in the US.

^ What company does that? A lot of the smaller shops are easy to point out (SafeLine Defense) because of the appearance of their plates, but others aren't as easy.