The Knee Trembler (Guy Pratt Signature Model) is an insanely good tremolo effect with unique LFO, designed in direct collaboration with Guy Pratt of Pink Floyd fame, perfect for his famous, One of These Days bass intros, especially when coupled with the Echosex Baby. If you miss the days when amps came with onboard tremolo, you ll love the Knee Trembler. It can be as smooth or as cutting of a tremolo as you would want. And keeping in line with Foxgear s devotion to excellence, it is absolutely transparent and noise free.