Armatus II Sizing

[South]

Looking at buying a LBX Armatus II plate carrier. I use medium plates, but the sizing of the carrier is a bit confusing on their website.

Medium Armatus sizing:
Small SAPI Plate; 8.75” x 11.75” SAPI Single Curve; 1” thickness
Medium SAPI Plate (recommended); 9.5” x 12.5” SAPI Single Curve; 3/4” thickness

Large Armatus sizing:
Medium SAPI Plate; 9.5” x 12.5” SAPI Single Curve; 1” thickness
Large SAPI Plate (recommended); 10.125” x 13.25” SAPI Single Curve

Is that saying the medium will fit small plates, but recommend medium, or is it saying small for the front plate/medium for the back.
And on the Large, medium plate up front, large in the back?