The short sleeved shirts are from Fruit Of The Loom, called Original T, and come in sizes S 35/37″, M 38/40″, L 41/43″, XL 44/46″, 2XL 47/49″, 3XL 50/52″ (measured all the way around the widest part of your chest in inches).
This table shows the measurements of the shirts themselves.
A Room With A View 