Transformers: United

Transformers: Generations is a 2010 toy line by Hasbro. Much like the preceding Universe toy line, Generations covers different eras of Transformers; here, the toys are based upon characters from Generation 1 and the video game Transformers: War for Cybertron, as well as the Transformers comics by IDW Publishing. The figures consist of new molds as well as redecos of ones originally used in the Classics and Universe lines. These Deluxe Class figures stand at about 5.5 to 6 inches tall and feature intermediate to moderate transformation levels.

The first wave of figures was released in July 2010. At the 2010 Cybertron Con in Shanghai, China, photos of upcoming figures set for release in Spring 2011 were unveiled.

The Generations line will continue from 2012 to 2013, which will include figures based on characters from the Transformers: Fall of Cybertron game. In addition, newer figures are released exclusively for the Asian market. These specific figures are known to collectors as "GDO" (Global Development Organization).

The initial line running from 2010 to 2011.

The second line running from 2012 to 2013.

The third line running from 2013 to 2014.

The fourth line running from 2015 to 2016

Transformers: Titans Return is a part of the Generations toy line that involves transforming action figures that are either Headmasters or Titanmasters (Headmasters that form the heads of titans) or just regular Metrotitans. The Headmasters are usually about 4-6 inches tall, while the Titanmasters are about 20-22 inches tall, same with the regular Titans.

Transformers: Reveal the Shield is a 2010-2011 expansion of the Generations line that also includes figures from or inspired by the live-action film series. The sub-line gets its name from the heat-activated silver sticker on each figure that reveals an Autobot or Decepticon insignia when rubbed. Over half of the Scout Class figures were canceled before production.

Transformers: United is the Japanese release of the Generations and Reveal the Shield figures by Takara Tomy. All figures in this line are metallic redecos of the Hasbro versions. The line originally ended in March 2011 with G2 Optimus Prime and eHobby exclusive three-packs, however, Takara Tomy continues to release figures in this line throughout 2012.

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Wikipedia