I selected the Forespar LC 10-18 EL-UTR. It's a 2.5" diameter, and extends from 10' to 18'. With my 115% jib, I've only ever extend it to about 12'. I also once used it to align my asymmetrical for deeper downwind angles, and it worked great for that too.
My mast already had a short track on the front with a ring. I didn't bother with the very expensive option of the longer track, toggle, and storage fitting to store it on the mast. While nifty, it would have doubled the cost. Instead I just bought the pole and 2 of their station mount blocks (Forespar 300042).
Most of the time when I fly it, I don't use a topping lift or a downhaul. I just click it into the mast ring, on to the sheets, and then pull the sheet tight to force it up against the sail. This does have the effect of pulling the pole against the forward lower shroud, causing scratching on the pole. I have in the past used the spinnaker halyard as a topping life and rigged a downhaul using a spare block at the base of the mast, which was far more elegant.
I also find that the no-topping-lift method requires moving the jib car all the way back, but even at that angle the sheet is pushing on the lifeline a bit.
In the future, I want to rig a permanent topping lift.
Here's some pics: