Excel Formula: Creater Unique Values using 1st 6-bytes for text

[issincorp]

I have a list of project codes (pro001, katk002) however, the cell also contains a comment next to the project code. I need to create a unique list of project codes using only the first 6 characters. Example:

Column A1
pro001 (comment1)
pro007 (comment2)
pro001 (comment)
kat002 (comment)
rdt005 (comment)
kat002 (comment)

I would like another column to display only unique project codes without the comment:
Column B1
pro001
pro007
kat002
rdt005

Can someone help me with this formula?

 

[iggydarsa]

=left(a1, 6)

 

[issincorp]

Thank you! How do I incorporate this 'left' formula in a formula to create the unique values so it display the following?

Column B1
pro001
pro007
kat002
rdt005