The Jimmy Page harness has all of the pots as push/pull pots. When they are all in their normal positions you have a standard Les Paul setup. Pull the bridge volume pot and you split the bridge pickup; pull the neck volume pot and split the neck pickup; pull the bridge tone pot and it puts bridge & neck pickups out of phase with each other; and pull the neck tone pot and it puts bridge & neck pickups in series together. In the end it means you apparently get 21 different pickup configurations! I still can't for the life of me remember all the options, but I have started to find various combinations that give a nice sound. There are a few clips on YouTube that explain it quite well. I bought the harness of eBay - a local guy offers them up - for about $85. He does a great job and I can certainly recommend him. All of this JP stuff came about after a build diary that Salo did here a couple of months back - I hadn't heard of it until then.