The whisker pole that I bought in '86 and still use on Windrunner: Is a Forespar, telescoping, 1 7/8 inches in diameter for the large tube, it extends to 12 feet, and collapses to 9 feet. It would collapse further but it has been bent.
It still fits nicely along the lifelines and bow pulpit. When in use it attaches to a fixed bail on the mast. It works very well with the 110-120 stock jib, it is just a mite short for the 150, but works OK. It is a bit heavy for the drifter, but again works OK.
I would buy another like it if I had to replace it.
Hope that this helps