Tamper-resistant receptacle

Leviton says a tamper-resistant receptacle has a shutter that blocks access to the contacts unless a plug with two or three prongs goes in. These receptacles were developed after children were hurt pushing keys, hairpins, paper clips, pens and other objects into slots.

The shutters open only when pressure is applied to both sides at once, as a normal plug does. Many places require them in homes, and code editions change, so check what your city enforces. Some are also weather-resistant or add USB ports. A licensed electrician can swap them.