The Envato Network is a great marketplace known by huge numbers of people. This December you can grab the December’s Free File of the Month which is designed by DeltaForce. The free file includes a stylish and clean set of modern backgrounds. There are 20 super amazing nice abstract backgrounds with high resolution (4000×3000 pixels).
Enjoy and find it useful for your commercial or non-commercial but you may not use the file in multiple projects unless you purchase licenses.
Download the Envato-December's Free File