Keeley K4COMP 4 Knob Compressor The award winning industry standard for stomp box compression The 4 Knob adds Input Clipping and Attack controls to the top of the the original Keeley compressor for easy adjustment Perfect for those that often switch live between single coils and hum buckers The sound alone will inspire your creativity A true audiophile and studio grade compressor with an exotic rack mount quality in a stomp box form