[C#] Question about an old thread

I have a question about an old thread:

Code:

forums.mydigitallife.net/threads/35723-C-Compatible-Windows-8-Product-Key-Decoder

First of all, the code in that thread works correctly, I'm not disputing that.

My question is about these two lines:

Code:

            // Check if Windows 8/Office 2013 Style Key (Can  contain the letter "N")
            int containsN = (digitalProductId[keyStartIndex + 14]  >> 3) & 1;
            digitalProductId[keyStartIndex + 14] =  (byte)((digitalProductId[keyStartIndex + 14] & 0xF7) | ((containsN  & 2) << 2));

Or in a simplified form:

Code:

 
byte b = ..;
int containsN = (b  >> 3) & 1;
b =  (byte)((b & 0xF7) | ((containsN  & 2) << 2));

First (b >> 3) & 1 checks whether the 4th bit in b is set.
Then b = b & 0xF7 sets the 4th bit to 0

But what is the meaning of | ((containsN & 2) << 2) ?
containsN is either 1 or 0.
1&2=0 and 0&2=0
0<<2 = 0
x|0 = x

So this piece seems to have no meaning? I could be wrong or I could be missing something, but this has been bothering me for some time now so if someone could clarify that would be great.

Thanks

 

I know what ContainsN is for, I'm just confused about the meaning of | ((containsN & 2) << 2) . It seems to me that this part has no effect on the value of b.