The scam with rebate vouchers and gift cards is they want your card info to charge for shipping but won't tell you that in the fine print is authorization to charge your card with negative-option subscriptions for crap that you'd never agree to had you been made aware of them. These charges repeat every month and canceling them is difficult and your card issuer may or may not agree with you that you've been scammed and may not refund your money. Don't do it.