This vest, XS - SM, has internal ballistic material and an external pocket for soft armor plates. Here's a quote from the manufacturer on the material and the pocket for the plates.
"Front panel measures 13.5"W X 13.5"H (from bottom of neck cut). Rear panel measures 16.5"W X 14.75"H (from bottom of neck cut).
Exterior body armor pockets for soft panels. Exterior body armor pockets will accommodate up to 8.5"W X 11"H soft armor panels."
The small will only take 8 by 10 plates you have to go to the medium and up for the 10 or 11" plates. I ordered a small based on the expert answer and it will not fit a 10" by 12" play
That will depend on the size of carrier. The small carrier will only fit the 8x10 size plates.
Size Small vest did not fit my Chase Tactical 10x12 shooter's cut plate. The pockets measured to be 9"x11". I don't know about the bigger sizes.