I use this on the back of all my cases: http://www.amazon.com/Sinjimoru-Sinji-Pouch-Adhesive-accessory/dp/B005ZWC4N4 http://www.cyberguys.com/product-details/?productid=76858

This version is also available but a bit pricey:http://www.walmart.com/ip/Card-Ninja/24698753