The X-Blender is a unique tool for the modern guitar/bass player.  It's a switchable series-parallel loop unit.  A parallel effects loop allows you to mix or blend the effects with a dry signal (unaffected signal), creating a far more complex tone from your guitar.  Let's say you love your old tape echo unit but don't like how it changes your tone.  With the X-Blender you can blend in exactly how much signal from the echo unit with the original unaffected signal from your guitar.  That is just one of the many uses for this pedal.