To purchase one or more shirts, enter $18 in the Amount field for each shirt purchased. In the Comment field, enter your name, your phone number, and your size(s). Choose from among men's S, M, L, XL, XXL, XXXL. (Limited quantities of S and XXXL.)
Be sure to click "PAY" when done. You can pay with any mainstream credit or debit card, or with Paypal.