Keeley Electronics Neutrino Envelope Filter, boxed.
"The Keeley Neutrino V2 is an amazingly toneful and compact form of the classic opto-coupler envelope filter. The Neutrino takes your guitar playing and creates an automatic wah sound based on your pick attack! Envelope filters or auto-wahs as they are often called, sound and react best when they are opto-coupler based. The opto-couplers used in the Neutrino are particularly smooth, giving you an amazing vowel-like tone. The Keeley Neutrino gives you 3 filter ranges, 2 directions, 2 ranges for the frequency center and a Peak control. Keeley has engineered a power supply voltage-doubler so you maintain the highest headroom for your tone. An incredibly tough build means it will last for many decades to come. Whether you’re in a jam band or playing funk, the Keeley Neutrino V2 delivers incredible vocal-like tone."