Sideral divides sound in Center and Sides (or Mid+Sides = MS).
With it, you can control the Sides level between -6 and +6 dB. This effect is 100% transparent and allows you to: add/remove ambience, presence and /or reverb from stereo recordings; stereo field control; sound design; noise reduction/restoration and you can even use it on home mastering.
On individual channels, you should use it for processing sounds that have phase problems (but where you want to keep the original characteristics) by slightly altering the signal by just 1 or 2 dB´s.
Note that, despite of the central meter shows both (Center and Sides), with this plugin, you can only control the Sides level (in red in the meter).