The iPhone 3GS retains the same design its predecessor used which featured a glossy plastic back with tapered edges which gives users a better grip of the phone. It also features metal buttons just like its predecessor's. The iPhone 3GS and its predecessor are almost identical though the 3GS is differentiated only by the latter's reflective silver text on the reverse side which now matches the silver Apple logo, replacing the 3G's grey text. Unlike its predecessor, the iPhone 3GS was available in white and black for both models (16GB and 32GB) although the current 8 GB model is only available in black. 

The reverse of the iPhone 3G (left) is almost identical to that of the 3GS, differentiated only by the latter's reflective silver text which now matches the silver Apple logo, replacing the 3G's grey text.