It is, it blocks 90% of 5ARII and even the other 2 types. But as you know, DHT is not the ultimate cause of ANDROgenetic Alopecia. The fact, why man lose hair, is, that the follicles, or the tissue is just genetically too sensitive to androgens.
TO ALL ANDROGENS.
Now, it's your job to make them stop working (on the scalp) and you finished it with male pattern baldness.
Remember; castrated men don't go bald. Simple: castrate your scalp.
It's not only DHT, it's even-more as well T and many others...