These hot-ends take in 1.75mm feed and extruide at 0.2mm. The nozzle is so small it's only suitable for PLA and will become blocked by any dust on the filament. This is not a good choice for your first 3D printer.

The brass nozzle is 30mm long and is lined with PTFE. The nozzle is secured inside a PEEK block. A tube of PTFE is used as a spacer. The nozzle is heated with a tiny 8 ohm nicrome heating element, as the heater is so small it reaches print temprature in a fraction of the time comapired to a heater block design.

Here's a video of one of the hot-ends in action.       http://www.youtube.com/watch?v=4mb9BjxOMFw

If you want to build one your self then I've made a guide on my website you can follow.        http://Genesismachines.co.uk/