Wonderous Item, Uncommon
This bag has a central pouch and four side pouches, each of which is an extradimensional space. The larger pouch is roughly 2 feet in diameter at the mouth, and 2 feet deep. It can hold up to 100 pounds, not exceeding a volume of 20 cubic feet. The side pouches can each hold up to 10 pounds, not exceeding 2 cubic feet. The bag weighs 10 pounds, regardless of its contents. Retrieving an item from the bag requires an action.
If the bag is overloaded, pierced, or torn, it ruptures and is destroyed, and its contents are scattered in the Astral Plane. If the bag is turned inside out, its contents spill forth, unharmed, but the bag must be put right before it can be used again. Breathing creatures inside the bag can survive up to a number of minutes equal to 10 divided by the number of creatures (minimum of 1 minute), after which time, they begin to suffocate.
Placing a School Satchel of Storing inside an extradimensional space created by another item such as a Bag of Holding, Handy Haversack, or Portable Hole, instantly destroys both items and opens a gate to the Astral Plane. The gate originates where one item was placed inside the other. Any creature within 10 feet of the gate is sucked through it to a random location on the Astral Plane. The gate then closes. The gate is one-way only and cannot be reopened.