I have one of these codes for sale. Regular Marketplace price is £3.40 via Microsoft Points. Yours for £3, save 40p and do without the hassle of having to buy 500 points. See below for details from Xbox.com:
Gears of War 2: Flashback Multiplayer Map Pack
Cost: 400 Microsoft Points (£3.40)
File Size: 116 MB
"As a special thanks to the fans, weve updated five popular maps from Gears of WarGridlock, Subway, Canals, Mansion, and Tyro Stationand made them available to download. This map pack is also available for free with an Xbox LIVE redemption code included in new copies of Gears of War 2. There are no refunds for this item. For more information, see http://www.xbox.com/live/accounts"
Thanks for looking!
£3 via PayPal Gift
Was £3 - now £2.75!!!
- Jay ITFC