coupon-voucher

Attach the coupon to the front of your letter.
把优惠券附在信的正面。
The winners will each receive a voucher for a pair of cinema tickets.
获胜者每人将会获得两张电影票的代金券。
Vouchers must be redeemed before September 14th so you'd better get cracking to cash in.
代金券必须于9月14日之前兑现，所以你最好快点。

redeem:http://www.etthink.com/thread-284333-1-1.html