We guarantee our product. If a customer would like to return products purchased fromwww.preval.com, the buyer must send an email (firstname.lastname@example.org) to make a return request. It is the responsibility of the buyer to pay for the return shipping, which can be done at any UPS or FedEX location. Preval does not recommend that our customers return Preval products via USPS. Preval will e-mail a return authorization, please print and include with returned product. Preval.com will issue an on-line credit for the return purchase, which can only be used for a future purchase on www.preval.com and not with any of our re-sellers. A 25% re-stocking fee will be charged to the credit card originally used on the order. Preval.com does not accept return purchases made from one of our re-sellers.