Personal Force Screen, Medium (5e Equipment)
From D&D Wiki
This is a tiny, lightweight device which can be used to generate a barrier of force around one's person. A medium personal force screen has a battery life of 50 minutes. You can spend a charge to activate or deactivate a force screen as a reaction. While a medium force screen is active, you have 50 temporary hit points and take no damage from the magic missile spell. You regain 10 temporary hit points, to a maximum of 50 at the start of your turn. If the temporary hit points provided by the force screen are reduced to 0, the force screen collapses and it loses 10 minutes of its battery life.
Weight: 4 oz.