If you purchased your iPhone 4 before September 30th, 2010 you'll be elligible for a free case from Apple. In order to get this case you'll need to download the 'iPhone 4 Case Program' app from the app store and follow the prompts on your screen.

1. Download the iPhone 4 Case Program app from the App Store.
2. Launch the app on your iPhone 4 and sign in using your iTunes Store account or Apple ID.
3. Select your Bumper or case.

For iPhone 4 purchases made before July 23, 2010, you must apply no later than August 22, 2010; otherwise, you must apply within 30 days of your iPhone 4 purchase. To qualify for this program, you must purchase your iPhone 4 by September 30, 2010.