What are they made of? 

I use silky,straight hair from the toko, to make the dreads.
The hair from Kanekalon isn't something I use often. The dreads never look the same when I make them with Kanekalon.

The rubber bands that I use to install the dreads usually come from the toko as well, but I also use rubber bands for horses. 
You can bring your own bands if you have them, but I prefer to buy them myself, because I know my brands 

How long do the dreads last?

The ones I make last long, I had my first set of blonde dreads for over 2 years. And I wore them everyday! 

Twisted 'machine' dreads fall apart after a few months. Because they are 'twisted' with a machine :p
I make my dreads with the 'rip n twist' method, I only use my hands.
No backcombing, no liquids and no hairspray.