HTML version of Flat UI includes:
--- Twitter Bootstrap 3 Framework based
--- Retina Ready Images and Icons
--- Custom form components
--- Sleek CSS3 effects
--- OOCSS approach
--- Easy configurable color scheme
--- New web-font and new web-font icons

PSD version of Flat UI includes:
--- PSD files
--- Layered (Shapes)
--- Retina Ready
--- Color swatches
--- Glyphs - svg format
--- font used - Lato