4K HD Wallpaper: Watch (Macro). Time. Clock
If you're a fan of hand watches, this image can be saved free under CC0 license and be used as homescreen phone, desktop background or in other projects that you might have... all of these from courtesy of talented photographer Tomasz Bazylinski.
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with many tablets)
HTC, Samsung Galaxy & iPhone: 1080x1920 (compatible with many phones)