I myself use a 15 degree fan jet. If I want the concentrated power of the pencil jet, I just place my 15 degree fan jet nozzle very close to the stubborn piece of dirt I'm trying to shift.
Fan jets lose their power the further away they are from the surface they're trying to clean. The benefit of the fan jet is that they clean a larger area in a single stroke than a pencil jet. To clean a large surface with a pencil jet would take a very long time.

Working out your Nozzle Size and Type
Say for some reason you lose your nozzle, or you want to have a spare, or maybe you want an entire backup lance in case your regular one packs in while on site, you'll need to find out the nozzle size and type your pressure washer uses.

To work out the size of the nozzle fitted to your particular lance it should have written on it somewhere the degree of it, either 0, 15, 25, or 40. It should also have next to this the nozzle type. The nozzle type of my pressure washer is 05. So, on my lance nozzle it says 1505, , 15 standing for my 15 degree fan jet, and 05 standing for my nozzle type.

If your nozzle doesn't have its size and type marked on it, or if you're just unsure, you can order a catalogue from Dual Pumps by requesting one from their website. Somewhere near the back of their catalogue is a nozzle size/type table guide, just type Dual Pumps into Google to find their website.

Using the Dual Pumps Nozzle Table
The two things you'll need to know is the bar and lpm your machine produce and use.
Next find the table in the Dual Pumps catalogue. It will be under spray nozzles, somewhere near the back.
Find the bar number that corresponds to the bar your machines produces, then from there you run your finger down the graph till you find the lpm your pressure washer uses.
You may not find an exact match on the lpm, just find the number that is closest to it.
Next you run you finger across the table to the left where you'll find your nozzle type and size in mm.

The Dual Pumps Online Table
If you can't wait to get your copy of the catalogue, you can view an online pdf version here. The nozzle table is on page 7: www.dualpumps.co.uk/images/spray_nozzles.pdf

Rotary Nozzle, a.k.a Turbo Nozzles

The turbo nozzle is a clever little piece of kit that combines the benefits of a 0 degree pencil jet and a fan jet. The opening on a turbo nozzle is 0 degrees, like with the pencil jet, however the jet is at an angle and rotates as the water comes out producing the wide angle you get with the fan jet.

This means a turbo nozzle has greater power at a distance than a fan jet and a wider cleaning angle than a pencil jet.

Now this is great for cleaning block paving or concrete as it should allow you to work a lot faster. However if you're cleaning wood, someone’s decking for example, it will be a bad idea to use a turbo nozzle as the ferocious power of it will most likely damage the wood. I guess you could turn the pressure down on your pressure washer but personally I'd rather not risk it.