T-Shirt plastic bags are the formal name for bags often used in grocery stores, pharmacies, and convenience store. Made of plastic, they have handles on the side that make them look like sleeveless t-shirts, thus accounting for their name. The bags are measured using the barrel measurement system. When shopping, you may see different fractions. All of these account for the common sizes of t-shirt bags, with 1/6 barrel being the most commonly used in grocery bags all over the world.