Femonized seeds

Do femonized seeds absolutely 100 percent gaurantee you female plants? And if so why would they even sell male seeds. Seems kind of pointless to put all this time and effort into a male plant and get nothing out of it. I'm a noob so mayb someone can help me out

For the most part, Just stay away from nirvana's autoflowers there fem are whatever, and most dont autoflower. Other wise they should be female, As long as you dont stress them , and turn them hermy:(.:thumbsup: