Electro-Harmonix Micro Q-Tron
The Micro Q-Tron is an envelope filter stompbox, designed and produced by Electro-Harmonix, a NYC-based guitar and bass effect manufacturer. The pedal is a so-called "micro" version of the Q-Tron+, a reissue of the pedal with the same name from the 1970s. Both the Micro Q-Tron and the Q-Tron+ are considered by many as being classic envelope filter pedals. They're used by artists like Graham Coxon of Blur, Stefan Olsdal of Placebo and Brendan Benson of The Raconteurs.
The Micro Q-Tron only has three controls; Mode (selects between three standard filter types, low-pass, band-pass and high-pass), Q (selects the intensity of the filter effect) and Drive (slightly overdrives the signal for a more noticeable effect). The pedal is suitable for both bass and guitar.
Chris Wolstenholme used the Micro Q-Tron during The Resistance tour. It's unknown exactly which song(s) he used it on.