<p class="MsoNormal" style="margin: 0in 0in 0pt"><font face="Verdana">Hi Tim, in simple words it&rsquo;s a servo controlled high speed needle valve assembly for fine tuning in flight.
You set the high speed needle a usual on the ground but have the benefit of tweaking it during flight.

Have a pic of itbut RCU image upload is down. I'll try later.</font></p>