I bought 50g of L-Theanine Powder from the Online Company, "Liftmode", to see if I could augment my considerable Caffeine consumption, by combining the two ie. I added the suggested serving dosage of 200mg to each of my 3-4 × daily, large "Iced Coffees", in which I had halfed my usual amount of "Full Roast". I was hoping to obtain the same desired effects from less. Or at least minimize the unwanted ones (ie."jitters" & cardio-pulminary strain). And it did all of these things. It's a subtle but very worthwhile helper :) Considering I am prone to being quite sensitive physically. At no stage during the last few months did I suffer from any ill effects whatsoever, which can sometimes occur with even the most benign of supplements, if they are sourced from questionable origins. Therefore, I am absolutely satisfied with the purity and quality of this product. As I am of all the supplements I purchase and receive easily, quickly, safely and reliably from "Liftmode". Every single time :)