There may be no such thing as a free lunch, but now customers who shop at Best Buy are eligible for a free Side Shield for the iPhone 4. The offer launches exclusively on July 28, and comes in the form of a clear, unobtrusive shield applied to the outer edges of the iPhone 4.

The Side Shield from invisibleShield was designed to address issues with antenna attenuation and has been tested and manufactured by ZAGG. This program will be available free of charge, including installation, to anyone who purchased or will purchase an iPhone 4 from Best Buy and will be extended to all existing Reward Zone customers. The solution will also be available to the general public for the retail price $9.99, including installation.

In addition, all consumers can take advantage of 20% off of any iPhone 4 case through Aug.7. Best Buy Mobile (http://www.bestbuy.com/mobile) offers an assortment of cases for the iPhone 4, along with a range of key accessories that serve to protect and personalize the smart phone.