The Tremster has that buttery, seductive tone like a vintage tube amp tremelo. It allows a wide range of control from very slow to head-spinning fury. A flashing LED displays the speed setting that has been selected. The T-Rex Comp Tremster is an analog pedal that uses a MOSFET transistor. It does not feature true bypass. However, it employs an on/off switch that is designed to bypass the sound without disturbance so that the pedal will not be heard when it is switched off. T-Rex pedals are handcrafted in Denmark.