This Santana Vintage Peace t-shirt is officially licensed and manufactured by Hi Fidelity Entertainment. The front is screen printed on a charcoal t-shirt made from 100% cotton.  No design is on the back.

Size,          Brand,                Armpit to Armpit, Top to Bottom
Medium     Gildan Heavy Cotton    19.5"                29.5"
Large        Gildan Heavy Cotton     21"                   30" 
X-Large     Gildan Heavy Cotton    23"                   31"
2X-Large   Gildan Heavy Cotton    25"                   32"