The model number was spotted in a UA Profile on Sprint Official website.
As the Sprint’s LG G3 model number is LG-LS990, It is Logical that the LG-LS991 is the Sprint Variant of LG G4.
Unfortunately, the handset’s Specs in details, such as Screen resolution, CPU, RAM size, Camera etc. Were not disclosed in the LG-LS991’s UA Profile, because Sprint and LG have decided to hide that information on purpose this time.
Based on the information revealed by the LG-LS991 UA Profile, The device will come with Android 5.1 Lollipop and the Software Version is “LS991ZV1”.
Early rumors suggest that the LG G4 is either arriving with a QHD display (1,440 x 2,560 pixels) or a 3K display (1,620 x 2880 pixels ), A&T LG G4 model number is LG H810 sports a QHD display, while the Verizon LG G4 model number is LG VS999, could come with a 3K Display.
Other rumored Specs of the LG G4 includes a 5.3-inch QHD (2,560 x 1,440) screen, a 16-megapixel rear camera with OIS+ and 3GB or 4GB of RAM.
By the way, the apps that the LG G4 could come preloaded with are listed in the UA Profile. Here are some apps from that list:
Google Play Games
LG Search (Google custom)
Sprint Installer(No app in Tray)
WiFi Off loader
To see the Full list of Apps, check out the UA Profile at Sprint official website here.