T-shirts have been used as a message board, since T-shirts first became popular in the 50's. Bold slogan designs take this to the extreme and work so well. One colour screen prints are really cost effective, especially onto white T-shirts (which cost slightly less than coloured shirts) so there's more profit on each sale for the charity to use.
These T-shirts were printed for Hope for Justice and their amazing campaign ‘No More Slaves.’ Hope for Justice exists to end human trafficking and slavery. Read about the amazing work that they do.