Ux 4. 0 Dark is a theme to be applied on LG phone, it is compatible with most LG stock ROMs and LG stock based Custom ROMs theme engine: LG G series LG G6 /LG G5 /LG G4 /LG G3 /LG G2. LG V series LG V30 /LG V20 /LG V10. LG K series. Theme Features Smart Dynamic UX 4.