riot shield
A modern shield used by police and some armed forces in riot control to protect the shield carrier from melee attacks and also thrown projectiles, or non-lethal weapons such as rubber bullets and water cannons.
Riot shields are typically made out of transparent polycarbonate and are designed to be shatter resistant, but are generally not ballistic resistant.
Riot shields can either come in two main variants, one that is one-handed that affords less protection but allows the user to use the other arm, generally to wield a baton. It has two handles, the left-most of which is held on to while the other keeps the arm in place. And another that requires both arms and provides full protection.
Not to be confused with ballistic shield which is identifiable by its opaque, often metallic appearance and with narrow viewing port.