Due to the relatively low price, and also the marketing of certain, more expensive, sellers of TKA, I was initially skeptical as to whether this extract would be any good. However, having tried it, I am now certain that it is not ineffective powder, and definitely contains a significant amount of TKA's active alkaloids.
I'm sure I wasn't alone in assuming that genuine TKA extract should be dark brown, but I now believe this is a myth. Apart from effect - which obviously, you can't assess immediately - I think the best indicator is bitterness, and Focus' TKA is unpleasantly bitter - and I'm someone with a high tolerance for strong/unpalatable tastes.
Of course, this is something that theoretically could be faked, but Focus is a reputable company, and so I discount that as a possibility.
When it comes to the precise strength of the effect, I must admit that I find it hard to tell- but this is only because I had already ordered a bottle of TKA from another seller, who I knew to be reliable, if also expensive, and so, since I started taking this as soon as I finished Focus' capsules, and since it can take a while for TKA to properly kick in, it was hard to tell which product was doing what.
Interestingly, the TKA from aforesaid other seller was only a shade or two darker than Focus' TKA, and this is an 'award winning' product, and one which I trust. So, there's further confirmation to me that the idea that TKA has to be dark brown is overblown.
This extract may or may not be as strong as the most expensive products, but I am convinced that it's the best value for money. There are definitely a lot of weak or fake products out there, some of which may be yellow in colour- but this is not one of them.
I will only be buying Focus' TKA from now on, but next time I'll buy the powder, and make my own capsules- I gather that capsules are better, because stomach acid has quite a negative effect on the absorption of TKA.
My only real reservation is that Focus don't provide the Eurycomanone content, as I think this would be helpful who are as uncertain about it as I initially was.