Hello Eric, here is the phone number to A/O (716) 772-5445. for some reason they do not post a sizing in either there catalog or on there website. But they are standard tee shirts sizes so if you wear a size medium then you would be a size small. If you have any questions on sizes just give the manufacture a call.
Does this shirt have the logo on just the front left side or is it also on the back of the shirt? Thanks!
Arthur(Certified Scuba Instructor at Scuba.com):
Hello, the main logo is on the back of the shirt. On the front there is the Amphibious Outfitters logo on the upper left.