Question: Recently, I find out that somebody uses my network traffic. I found his `MAC` address and now I wanna find full details of his device. I tried: <http://www.macvendors.com/> and such this, but the response was only the name of manufacture. Tnx from anybody who helps me( or says a better solution to find him:) )
EDIT: Anybody who has another way to find him, tells me.

Answer: 
Just searching on the MAC will only give you the vendor. It will never show you in which hardware the component with the MAC was used. (Think of it as finding the vendor name for a lightbulb, which does not tell you in which device the bulb was used).

But given that you have the MAC and almost certainly the IP, you can use tools like nmap to find out more. If you do not like command line tools then try [the zenmap wrapper](https://nmap.org/zenmap/) around nmap. This usually will tell you which OS the device is running. That way you have a good idea if it is a phone (windows CE, android, ios or a PC (linux, BSD, windows).

Once you know that you can start to refine. E.g. if it turns out to be a windows device try `\\ip\c$`.
I have another idea for this purpose: what if somebody , on purpose , set own wifi without any password and the thief could connect again!

I think in that case we have more chance to discover what device is connected to our router.