I wish I put this in my build but I finished all my wiring before I saw it. It's a PLED. This is a shunt resistor that allows the rest of the led to still work if one fails open and prevents you from losing power for your whole string. It's a nice feature and well worth the price. It goes parallel with the LED and nuclearheli on reefcentral has it on his Version 2 build. Great Idea and very well planned. His work is just amazing.
http://www.youtube.com/watch?v=wH4q-CrnSJk
he's even got a video on youtube about it.
Enjoy and read his build thread you can get everything you need from it.
thanks
Erick