They are for KDE menu.

To install user-wide:

Copy or link branding.svgz (default) to ~/.kde4/share/apps/desktoptheme/default/widgets/branding.svgz
Copy or link branding.svgz (oxygen) to ~/.kde4/share/apps/desktoptheme/oxygen/widgets/branding.svgz

To install system-wide:

Copy or link branding.svgz (default) to /usr/share/apps/desktoptheme/default/widgets/branding.svgz
Copy or link branding.svgz (oxygen) to /usr/share/apps/desktoptheme/oxygen/widgets/branding.svgz