The Vintage-style Electro-Harmonix Pulsar Variable Shape Tremolo Pedal boasts a variable wave form that nails smooth, vintage tube-amp trem tone as well as giving access to deeper levels of watery waver. Control the intensity with Rate and Depth knobs, while affecting the overall character of your guitar sound with a Shape knob. Red LED lights in time to the pulse. If you can't get into the Electro-Harmonix Pulsar, you'd better check your pulse.