This article discusses software internally used by Apple.
Acquiring a copy without Apple's consent is illegal and may result in being scammed.
ScreenShotr is an internal macOS application used for taking screenshots of prototype devices running internal firmwares. The screenshots are taken at the device's resolution. It also appears to be able to take screenshots of devices which have been ran through Xcode and have the Developer preference bundle. One of its interesting features is the ability take screenshots wirelessly, most likely using a similar method to Xcode 9's wireless debugging feature.