Of course you were supposed to buy one caddy for each
CD-ROM you had,
 load them once, and then insert the appropriate caddy into the drive.
 Used like that, they're easier to use than loose CD-ROMs in a
 conventional tray-type drive.
 However, most people were too cheap (:-)) to buy enough caddies (they
 weren't that cheap IiRC), and there is a definite knack to loading them
 without dropping the disk. When you get used to them they're not that
 bad, though. 
The company I worked for was too cheap to buy more than a couple.
I seem to remember the caddies were around $40 each, but that may
be just a poor memory.
--
Eric Dittman
dittman(a)dittman.net