WE CONVERT YOUR NIKON SA-21 TO SA-30 COOLSCAN FOR NIKON 4000 5000 SCANNERS ONLY. This only works on these models. That\'s correct, you send us your SA-21 and we convert it to the functionality of an SA-30 so that you can scan either short strips of 35mm negatives or full length rolls up to 40 frames. This upgrade does NOT include a takeup reel, you simply open the little door on the back and run the scanner on its side. Here are the steps: 1. make payment 2. well pack and ship us your SA-21. 3. We test your unit and do the modification. Although we generally complete these in 48 hours, please allow up to 3 to 5 business days. Please call 706 540-3285 or email if you have questions 1 pm to midnite eastern time. I\'m Rick and i\'m here to help you.