Mk I through Mk VIII:
These were the first prototypes of the 3211 grip. Some were merely CAD designs and never actually built.

Mk IX: 
Two of the Mk IX versions were sent out to early adopters of the design, and a few more were test subjects in the shop.

Mk X:
The first "production" version of the 3211 grip. About 20 were produced in two different colors (black and coyote) and 3 different grip textures (Classic, Pumice, and Smooth)

Mk XI:
Mk XI was the first 3211 grip to be offered in Full Size (17 round P320 mags) and Compact (15 round P320 mags). The main difference between Mk X and Mk XI is a slightly different angle at the top front of the magwell where it meets the frame, allowing mating to the Springfield Prodigy Compact frame without having to remove material from the grip. 3211 Full Size or Compact grips are able to be installed on any 1911DS/2011 frame.