iPhone 4 Bumper, Apple Wiki
The Apple iPhone 4 Bumper was released by Apple in June 2010 as a protective cover for the iPhone 4. It covers the metal band around the perimeter of the iPhone while leaving the back surface visible. The iPhone 4 had a highly publicized issue in which the antenna configuration could lead to reduced signal reception if the user held the phone in a particular manner. On July 16, 2010, Apple began offering such customers a free bumper to insulate the antenna during use. The bumpers were withdrawn
iPhone 4, Apple Wiki
iPhone 4 - Wikipedia
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Review: Apple iPhone 4 Bumpers
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