The ELECTRO-HARMONIX / Micro Q-Tron is an envelope filter that recreates the Q-Tron effect of the legendary Mu-Tron filter pedal in a compact size. It changes the cutoff frequency and filter pitch according to the magnitude of the input signal, producing a captivating filter sound. The simplified controls allow you to quickly achieve your desired filter sound. A switch cap is included as a bonus. Velcro is attached to the back.