Steel Wool. Light Painting
4K HD Wallpaper: Steel Wool. Light Painting
This is a long exposure picture that gives this effect like a "light painting". From here the image can be saved free under CC By license and use as lockscreen phones and desktop backgrounds.
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)