The phrase "rear panel" refers to the back part of an object or device, typically a piece of equipment or gadget, where the connectors, inputs, or controls are located. Full definition
The image leaked on the social networking site shows the blue rear panel of the device. (androidheadlines.com)
Both tablets have undergone a slight cosmetic makeover, swapping out the sleek black soft touch rear panel for a black plastic textured finish. (laptopmag.com)
It actually has a glass rear panel, which seems to be the trend these days. (neowin.net)