TC Electronic G-Major 2

This is the Flagship rack unit currently available from TC Electronics

The effect that Matt uses this unit for can be heard on live on H.A.A.R.P (which he kicks on after the second chorus) is what's known as 'zero-through flange'; which, incidentally, is the earliest form of flange, back when recording engineers were pinching the actual tape to get the effect. However, zero-through flange is available on very few conventional flanger pedals.