"Reward Redemption" scam. They claim you won a $100 award, but it is a scam.
I thought this might have been a prize from a survey I participated in. Most of them have a $100 gift card sweepstakes. However, when I asked where the prize came from, the person on the phone was evasive. Furthermore, they say "you can use these vouchers at many retail stores." There's no clear indication that this is a single, $100 gift card, so this could be $1 at 100 stores or $5 at 20 stores... basically one of those coupon books that our kids sell at school fundraisers.