There is only one company making MP-44 KO (although they've tweaked it several times) and the small backpack is the latest version. ShowZ has it on sale. There were a couple of white leg versions with the voice chip in the huge backpack like the real MP-44. Version 1 was terrible, but v2 was a bit better but still prone to the hips/waist gears crumbling. Silver leg version still has the big backpack, but is similarly as good as v2. The the KO factory developed a version without the voice and slimmed down the back. They first did the black/shattered glass/EVA colors and then the v4 white leg version. Many of the complaints about v1 are now cleaned up, although the new back didn't consider the "jetpack" and "Starscream shoulder intakes" accessories very well so be aware. If those looks are important then v2 or silverlegs would work better.