I've tried a lot of different Pre Workouts that are caffeine free as the caffeinated ones give me heart palpitations. I came back to Cutlers Amplify because I have found that it gives me the best results over all others. I just bought three more cans so I don't run out. I'm a bit of a hoarder when it comes to my supplements. This used with Cutlers Liquid Pump gives me insane pumps and energy. I can easily goe for two hours in the gym compared to dying out after an hour with others. Plus, no jitters, no hesrt palpitations, no loss of sleep.