In 1983 Commodore Company to try to sell warehouse stock of VIC 20 and decided to rename VIC 20 to VIC 21 by packaging Commodore 16K RAM expansion pac together with VIC-20. They also stick new label (VIC-21) on old VIC-20 boxes and call it "SUPER-VIC". In real life it was exactly the same computer as VIC-20 with additional RAM expansion. This model is know to be rare only if its in whole package with box and matching serial numbers, otherwise is just VIC-20. Very rare set. Highly demanded in collectors world.