If you want to kill weeds and maintain your lawn, this is the real deal:
Professionals use Q4 because it is a mixture of the herbicides that kill nearly all weeds. I used it for the first time on my lawn last year, and every single weed died. One application. I had some weeds that are violets on my lawn which never reacted to any herbicide. They are all gone. Lawn remained okay. I would not use this in the summer when the lawn is stressed, but I ordered some last week and will be using it this spring again.
It's a concentrate, so you need to mix it. You also need a sprayer for it. I bought an electric sprayer just for this job. Was worth it.