This is a magical network that goes in series with the positive lead of the Fast-15 driver.  It has only three parts, all in parallel.  The total resistance is 0.36 ohms so it is barely there.  Transparency is top notch. 
 
Gives the driver flatter top end response for extended listening enjoyment.   Unit can be soldered like any other crossover, or used as shown connected to the amplifier binding posts.   Board is designed with double thick gold traces and is thin enough to be flexable to releave stresses on the amplifier binding posts.
 
Price is for one pair.