Teeka

Atari VCS - CX2600 Sunnyvale Edition is the original 1977 Atari Video Computer System, and this particular design was only produced for one year. Because it features six chrome-like switches and has heavy internal RF Shielding, some collectors refer to this as a "Heavy Sixer". At first glance it looks just like the CX2600 that follows in 1978, but it is noticably heavier when compared, and has some extra plastic molding around the back and sides of the unit. These units were manufactured in Sunnyvale, California, and there is a tag on the underside from the manufacturing plant to indicate this. There is also a serial number on the unit itself with a matching serial number sticker on the box. The later model was manufactured in Hong Kong.

Bibliograpphy
http://www.atariage.com/2600/archives/consoles.html