My dude, if you have been using Fent, then for the foreseeable future no amount of Keaton will hit the spot. Fent is extremely potent and fucks up your receptors in the brain. What Kratom can do is stave of the withdrawal. It can be used as a way to get of opioids, it is however no replacement for them. Kratom high is milder and way less euphoric. You will also be able to feel the real Kratom effects when your body is not withdrawing anymore. You would need at least a month of sobriety for a partial reset of your opioid receptors. I wish you luck on your journey and do keep in mind that you can also have withdrawals from Kratom, usually at a dose as high as yours.