This is one of my favorite & free fader/meter plugins, now updated.

HOFA Plugins has updated the free 4U Meter, Fader & M/S-Pan plugin.

Besides a revised user interface the update includes the following improvements and changes:

• phase flip for left/right separately
• extended trim to mute one side
• isdrag & drop of audio files for EBU R128 and peak level analysis (very nice)
• disabled meter won't be processed so it can also be used as lightweight fader/panning tool

http://hofa-plugins.de/en/plugins/4u/

The plugin can be installed using HOFA-Plugins Manager which can be downloaded here.