This is a dual compression pedal has the beautiful circuit from the Professor Compressor and a Operational Amplifier based compressor with controls for Hi tone and attack. The DreamTone Hi Tone control is a sorely needed feature to the realm of Compressors. Most wash out your highs or cut them off in the compression stage, wouldn't it be nice to add some back, now you can! One side of this effect is made with carefully selected components including Panasonic caps and National Semi conductor Transistors, and a NOS Signal Limiting Compressor IC on a silver solder traced wafer epoxy board, the other is a Point to point wired and epoxy coated a true work of art. Dual True By-pass switching with two miniature LED's to remind you what's on. If you are looking for a good compressor you can't go wrong with the Compendium!