What is the bottom of a pouch called? The bottom gusset is the additional material at the bottom of the bag which gives it its capacity for expansion. Stand up pouches can be made to meet your exact specifications, but typically the bottom gusset of the pouch is one of three different styles: Round Bottom Gusset, K-Seal Bottom, or Plow Bottom. What is flat bottom pouch? Flat Bottom Pouches have completely flat bottom and so they are known as “Flat Bottom Pouches”. These are also known as “Box Bottom Pouches, Block Bottom Bags or 8 Side Seal Pouches”. Flat bottom pouches are the premium packaging option of choice. What are pouches used for? A small bag often closing with a drawstring and used especially for carrying loose items in one's pocket. The definition of a pouch is a small bag used for carrying things.