Air Pocket

This breathing aparatus holds up to four hours of breathable air in an extradimensional space. After the air is depleted, it takes one hour of inactivity in an oxygen rich space for it to recharge. 

Placing an Air Pocket inside an extradimensional space created by a handy haversack, portable hole, or similar item instantly destroys both items and opens a gate to the Astral Plane. The gate originates where the 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 can't be reopened.

Notes: Utility, Container