The CX2600 "Light Sixer"
These models were introduced in 1978 and stayed in production for about two years. The thick molding on the sides and curved molding on the front gave way to thinner and more sharply angled molding reducing the weight of the system. The front right and left molding are angular and overlap the woodgrain. The thick RF shielding remained until the four switch models came out. Atari also produced a version of the "Light Sixer" for Sears, which had some minor aesthetic differences to the Atari-branded console
Source: Wikipedia, "[en.wikipedia.org/wiki/Atari_2600_hardware%23CX2600_.22Light_Sixer.22 Atari 2600 hardware]", available under the CC-BY-SA License.