What does the C3 mean in a 220-c3

[buenhec]

I recently purchased a 220 c3, and tried to purchase a CTAC holster, unfortunately CompTac told me this is a new model and they dont make it for that model.

I thought a 229 compact is the same size as the 220 compact, Comptac says the 220 is thinner. Is this correct?

What other shiftable IWB Kydex holster would you recommend?

 

[1911 guy]

Compact, concealable and ... I forget the last one they tagged onto it.