Knox FDC Lock p/n 3110 F00-105713 Knox Box Fire Department controls

I'm afraid I don't know a lot about this, came in a lot of things I purchased at an auction... I do know these complete sell for well over 450$, but you already know that I assume... It appears to me that it is missing the round inner lock portion...but I assume that is the least expensive portion and would be easily replaced... Offering a great deal, as you'll need to attain the round inner piece...from Knox or other resellers, unless you already have one..