Even if it isn't baseball season, you've got a double header going on -- all the time. As a grandfather of twins, you are in an elite club.
Shirt has the text DOUBLE HEADER in scripted letters with GRANDFATHER OF TWINS underneath. You'll be the all-star wherever you go (especially with your twin grandchildren).
Shirt is a 100% cotton t-shirt in Navy or Black colors. Pre-shrunk to make sure your size is maintained throughout several washings, and classic fit, meaning it is not form fitted in the sides. (sizing chart)