Hi,
The extender is a brand name. We sell these in, 2 x 4 foot (8 ft) and 3 x 4 foot (12 ft). These are very light, cheap and cheerful.
The custom made poles are based on the universal range (next price band up) and these can be tailored to however many sections you want of whatever length you want. This is the type of pole that marc al is referring to. You will find them on the website at the bottom of the page for the universal pole range.
Telescopic refers to all the poles that slide down inside each other, currently we sell extender, universal, facelift and predator in this range. The other type of pole is a modular pole which has sections that put together.