try doing a search for dread size or dread diameter. i could tell you exactly but i want to see if you can find it. after you search if you still havent found it, i will show you which thread this has been discussed in.
Use the "Search" button and you will find a lot of threads on the topics you are looking for. There are a lot of topics on dread sizes. There are also a lot on how to make dreads. Some members here make dreads to sell as well. I'm not sure if they will give up their exact method for making dreads, but there are a lot of "how too's" in here.