Made by the Chinese manufacturer ToToLe.
Fundamentally a blend of salt, sugar and MSG, but also includes E635 – disodium ribonucleotides – to provide synergistic umami.
The combination of MSG and E635 boosts the effects of MSG, allowing you to use less MSG to achieve the same flavour-enhancing effect.
ToToLe explicitly market the product as a way to use less MSG; their website advertises it as “one spoonful is worth three spoonfuls”.