The following are the total storage capacity for each of the listed control boxes
CB450 - 450MB
CB460 - 4GB
TD510 - 16GB
TD520 - 16GB
Understand that this is total storage - used for file storage in the CB450/CB460 and in the TD5XX boxes it is Total Memory for the Software, Operating System and Storage.
As a rough indicator, a Design will often be ~5MB in size