Making a purchase from someone you don’t know or trust is a risk. When you go to Chipotle, you know exactly what you’re getting, there is no risk (oh wait, maybe that was a bad example). When you buy an apple from your local grocery mart, you don’t need any assurances, you just buy it.
But when you see an ad on Facebook for ‘combat Kevlar gloves’ which punch through anything, and then it is being sold on some simple e-commerce store, built off of Wix.com … you feel it in your gut “oh… I don’t know these guys, can I trust them? How do I know they’ll ship my stuff, and can I return it if I don’t like it?”
Guarantees are great for this.
Including a guarantee on your home page will be another ounce of potent trust juice, serving it straight up. It goes without saying but we’ll say it anyway: make sure you honor your guarantees if you are promoting them! Don’t say it unless you fully intend to implement them.