Model / Base system & starting price      
450A
3"Aluminum w/DVD Bay, 2.5" Bay, COM/LPT/WiFi/TV, For Home Theater PCs. DC12V-in, Small & Quiet.
400R
2.6" Small Aluminum Case more room for taller CPU fan, up to 2 HD Bay, all I/O ports. DC12V-in, VESA mount.
400S
2.6" Small Aluminum Case,3.5" Open Drive Bay or,Two 2.5" Swap HD Bay
500D
3.5" Aluminum Case with 5.25" Large Bay