The SN-42 armour vest is unique amongst newer interpretations of this concept in that it is but a single plate that protects the frontal torso. For some reason, the idea was never revisited.
The SN-42 is a Soviet armoured vest produced and issued to assault engineers during the Great Patriotic War. It consists of a 2.2mm thick steel plate shaped like a cuirass, which provides protection from shrapnel and pistol fire (the newer SN-46 is slightly thicker and heavier, capable of stopping steel-core 9mm bullets). These vests are not particularly popular for most applications, though an increasing number of Federal Police officers have begun using them. It's not the weight or burden which makes the SN-42 insufferable, but rather the Oceanykan heat, since it acts as a small furnace for a person's torso.