When's it due in?

1- try to explain better what you need, this a general recommendation valid for maybe other questions you will try to get answers for.

2- for such request start with a search engine as google and try to find already available explanation either via companies technical sheets or magazines.

3- CR4 is NOT here to solve school work or as a training site for beginners and if the need is basic knowledge (as it seems) you should learn it by yourself.

4- after you read and already have a knowledge you may ask for detail explanations.