On sale this amazing device by Ernie Ball . Smaller than the regular Ball's volume pedals . It has both - tremolo and ambient reverb . Hard to find anything close to it . I like placing it before a distortion or fuzz pedal , when you can cut the signal with tremolo (very sharp ) , and have a "helicopter" sound with this control of the speed . For me this model out of the whole series had the most sense . Perhaps the Overdrive expression can be also cool , but overdrive pedals in general are very subjective .

Anyway , mine works well . Collectible as it is very useful and no longer in production .